MnII-Doped Cesium Lead Chloride Perovskite Nanocrystals

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Functional Nanostructured Materials (including low-D carbon)

MnII-Doped Cesium Lead Chloride Perovskite Nanocrystals: Demonstration of Oxygen Sensing Capability Based on Luminescent Dopants and Host-Dopant Energy Transfer Fangyuan Lin, Feiming Li, Zhiwei Lai, Zhixiong Cai, Yiru Wang, Otto S. Wolfbeis, and Xi Chen ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b06329 • Publication Date (Web): 15 Jun 2018 Downloaded from http://pubs.acs.org on June 15, 2018

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ACS Applied Materials & Interfaces

MnII-Doped Cesium Lead Chloride Perovskite Nanocrystals: Demonstration of Oxygen Sensing Capability Based on Luminescent Dopants and Host-Dopant Energy Transfer ⊥

Fangyuan Lin,† Feiming Li,† Zhiwei Lai,† Zhixiong Cai,† Yiru Wang,† Otto S. Wolfbeis and Xi Chen,*,†,‡ †

Department of Chemistry and the MOE Key Laboratory of Spectrochemical Analysis &

Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China ‡

State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005,

China ⊥

Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg,

Regensburg 93040, Germany *Corresponding author: X. Chen, E-mail: [email protected] §

F. Lin and F. Li contributed equally to this work.

KEYWORDS: perovskite, Mn:CsPbCl3 NCs, non-noble metal phosphorescent dopants, hostdopant energy transfer, oxygen sensing, reversibility

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ABSTRACT The design of photoluminescence-quenching probes (PLQPs) for molecular oxygen (O2) is always a large space to explore. Luminescent semiconductor nanocrystals have been proposed as emerging oxygen-responsive probes, but the inherent O2 sensing of phosphorescent semiconductor NCs has not been reported so far. Here we demonstrate the O2 sensing capability of MnII-doped CsPbCl3 nanocrystals (Mn:CsPbCl3 NCs) and reveal the role of O2 on the optical de-excitation process of such perovskite nanocrystals (PNCs). By adjusting the amount and distribution of MnII dopants, as well as the host-dopant energy transfer (HDET) process in PNCs, we highlight that O2 can reversibly quench the MnII emission due to their temporarily disturbance to the ligand field of near-surface MnII dopants in PNCs. In phosphorescence mode, the PL intensity of the Mn:CsPbCl3 NCs is quenched by 53% on going from 0 to 100% of O2. The Stern-Volmer plot is good linear in the 0-12% O2 concentration range. High sensing reversibility and rapid signal response are also achieved. In our perception, the mechanism study makes our PNCs candidates for the optical probes of O2, and it is enlightening to explore more possibilities of the inherent O2 sensing based on the semiconductor doped-NCs (not be restricted to MnII-doped PNCs) with phosphorescence emission. INTRODUCTION Oxygen sensing has attracted interests for a long time due to its significance in numerous applications including environmental sciences, clinical medicine and biotechnology.1-2 In current approaches, optical oxygen sensing using photoluminescence-quenching probes (PLQPs) has become a competitive method that is superior to the use of a Clark electrode owing to its low oxygen consumption, minimal invasiveness, good reversibility and suitability for device


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miniaturization.1-2 Dynamic quenching of luminescence occurs when the luminous state of PLQPs is affected by molecular oxygen (O2). Numerous phosphorescent compounds can act as oxygen-responsive PLQPs because of the feasible electronic energy transfer from their longlifetime excited state to the triplet ground state of O2,3 examples include the noble-metal ligand complexes,4 fullerenes,5 metal-organic frameworks (MOFs)6 and others. In addition to these O2sensitive

molecules,

certain

luminescent

semiconductor

nanocrystals

with

attractive

characteristics such as outstanding optical properties, enhanced stability and large surface-tovolume ratios,7 are also known to be emerging PLQPs for O2. However, most of them are some functionalized quantum dots (QDs) that relying on the phosphorescent sensing centers (noblemetal ligand complexes or polycyclic aromatic hydrocarbons) placed on the surfaces of QDs.8-11 In this case, NCs simply act as energy donors for the foreign phosphorescent molecules, and the sensing capability of NCs for O2 is in the lack of use. Actually, the inherently O2-sensitive semiconductor NCs work in a different sensing mechanism. They include a few II-VI semiconductor NCs,12-14 whose exciton emission (about ns-scale lifetime) can be quenched when O2 extract electrons (photoexcited electrons and extra surface electrons) from these NCs. This deepens the development of NC-based PLQPs for inherent O2 sensing, but there is still a large space to explore. Inherent oxygen sensing of phosphorescent semiconductor NCs have not been reported so far. Recently, lead halide perovskite NCs (PNCs) have been attractive optoelectronic materials for light-emitting diodes (LEDs), lasers, photodetectors and solar cells.15-19 This is because of their high-quality photoluminescence (PL) emission, tunable spectra, good charge transport and defect tolerance ability.20-23 In addition, the highly ionic composition, dynamic surface ligands and ultimately low formation energy16 of PNCs confer themselves sensitivity to environmental


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conditions including humidity,24 temperature,25 gaseous HCl,26 NH327 and also O2. For the organic-inorganic hybrid perovskite, O2 can passivates the intra-gap trap states of MAPbI3 NCs by oxidizeing the interstitial iodine and thereby leads to the PL brightening and quantum yield enhancement.

28-29

For the all-inorganic perovskite, because of an O2-induced competition

between PL quenching (from the photoexcited electron capture) and PL brightening (from the adsorption passivation of excess surface electrons), the reversible dimming of exciton emission can be observed in CsPbBr3 NCs.14, 30 Thus, luminous PNCs have become the promising probes for inherent oxygen sensing. Recently, we have been focused on a new representative, MnIIdoped CsPbX3 nanocrystals (Mn:CsPbX3 NCs, X = Cl, Br), where MnII ions partially replace PbII ions in host PNCs to form MnII dopants.31-34 The comparable energy levels of the band gap of CsPbX3 host and the 4T1→6A1 emission bands of MnII dopants results in the host-dopant energy transfer (HDET) process,35-38 which is similar to that of some other MnII-doped colloidal QDs (ZnS, ZnSe, CdS, CdSe, etc.).7,

39-40

HDET activates the spin-forbidden d-d transition

(4T1→6A1) of MnII dopants. Thus, except for the remaining band edge emission from the exciton recombination of host CsPbX3 NCs, a new MnII emission (~ 580 nm) appears with ms-scale lifetime due to the affected MnII ligand fields.41 Doping MnII ions also improves the thermal stability and the luminous efficiency of PNCs. 38, 42 These lay the foundation for phosphorescent O2 sensing utilizing Mn:CsPbX3 NCs as the feasible PLQPs. In this study, we introduce Mn:CsPbCl3 NCs into the family of O2-sensitive PLQPs for the first time. The PNCs were synthesized with uniform size, good crystallinity and adjustable PL emission. Then the effect of O2 on the optical characteristics was demonstrated using testing films of the PNCs during the inter-switching between N2 and O2 environments. In the case of limited sensitivity of exciton emission to O2, the efficiently PL quenching and lifetime decline of


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MnII emission is observed. By investigating the Mn:CsPbCl3 NCs with incremental doping levels and adjustable HDET process, we elucidate the exact role of luminous MnII dopants on the oxygen-sensitive PL emission. We also locate the oxygen-preferential species in Mn:CsPbCl3 NCs by analyzing the PNCs synthesized under rising temperatures. Such mechanism behind the inherent O2 sensing capability results in the rapid and reversible phosphorescence dimming of MnII emission. Therefore, we develop the attractive potential of Mn:CsPbCl3 NCs for the roomtemperature phosphorescence detection of O2. EXPERIMENTAL SECTION Chemicals and Reagents. Cs2CO3 (99.9%), lead stearate (PbSt2, 99.9%), MnCl2 (99.0%), oleylamine (OAm, 90%, analytical grade), oleic acid (OA, 90%, analytical grade), octadecene (ODE, 90%, analytical grade) and trioctylphosphine (90%, analytical grade) were obtained from Aladdin (Shanghai, China). OAm, OA and ODE were dried under vacuum before utilization. Hexane (97%, analytical grade), ethyl acetate (99.5%, analytical grade) and hydrochloric acid (HCl, 36.0~38.0%, analytical grade) were purchased from the Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). Deuterated chloroform was purchased from Cambridge Isotope Laboratories (America). N2 and O2 gases (99.9%) were bought from Xiamen Oxygen Manufactory (Xiamen, China). Characterization. The corresponding composition of Mn:CsPbCl3 NCs were determined using inductively coupled plasma (ICP-MS) on an ELAN ICP-DRC-qMS (PerkinElmer, SCIEX, Canada). Transmission electron microscopy (TEM) images were performed on a JEM-1400 transmission electron microscope (JEOL Electronics, Japan). High-resolution TEM (HRTEM) and elemental mapping images were obtained from a JEOL 2100F field emission HRTEM. Xray diffraction (XRD) patterns were conducted on an X-ray diffractometer at 40 KV/15 mA,


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using Nickel-filtered Cu Kα radiation in the incident beam (Bruker D8 Advance, Bruker AXS, Germany). The room-temperature electron paramagnetic resonance (EPR) spectra were achieved using an EMX 10-12 (Germany), and the data were gathered at 9.84 GHz microwave frequency and 20.07 mW microwave power. Fourier transform infrared (FTIR) spectra were collected from a Nicolet 380 spectrophotometer (Thermo Electron Corporation, America). 1H nuclear magnetic resonance (NMR) spectra were recorded on a Bruker AV500 NMR spectrometer (Germany) at room temperature. Photoluminescence emission spectra were collected from a FL4500 spectrophotometer (Hitachi Co. Ltd., Japan). Absorption spectra were recorded using a UV-2550 spectrophotometer with one pair of 10 mm quartz cell (Shimadzu, Japan). PL decay curves were obtained from a FLS980 time-correlated single-photon counting (TCSPC) system (Edinburgh Instrument, UK). Absolute PL quantum yield was also measured on FLS980 instrument (excited at 365 nm) with integrating sphere. The true color images of corresponding samples were taken using a 5D2 camera (Canon, Japan) under UV excitation at 365 nm. Synthesis of MnII-doped CsPbCl3 nanocrystals (Mn:CsPbCl3 NCs) in single step. Mn:CsPbCl3 NCs were synthesized via a heat-up strategy within a few minutes. Typically, ODE (5 mL), OA (0.5 mL), OAm (0.5 mL), Cs2CO3 (0.1 mmol), PbSt2 (0.1 mmol) and MnCl2 with different feed ratios (0.3 mmol, 0.6 mmol or 0.9 mmol) were sequentially loaded into a 25 mL 2neck flask. The mixture was heated up from room temperature to the preset temperature (100 ºC, 120 ºC, 140 ºC) under atmospheric stirring, and then was immediately cooled by ice-water bath. Purification of perovskite NCs. The crude product solution of various PNCs was respectively centrifuged at 10000 rpm for 10 minutes to remove mother liquor. To separate the redundant reactants and the side products absorbed on the surface of nanocrystals, the achieved precipitates were washed with hexane/ethyl acetate for two times by centrifuging. The obtained


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PNCs were dispersed in hexane to make colloidal solution (of the same concentration) or vacuum dried to be powders for further characterization. Synthesis of undoped CsPbX3 nanocrystals (CsPbX3 NCs, X = Cl or Br). CsPbCl3 NCs and CsPbBr3 NCs were synthesized in the method of hot-injection. To prepare Cs-oleate solution, the mixtures of ODE (30 mL), OA (2.5 mL) and Cs2CO3 (2.45 mmol) were dried under vacuum and then heated at 120 ºC under N2 atmosphere, until the Cs2CO3 was completely dissolved. To prepare lead precursor, (5 mL ODE), OA (0.5 mL), OAm (0.5 mL), PbCl2 or PbBr2 (0.188 mmol) were added into 25 mL 3-neck flask and then dried under vacuum at 150 ºC. For CsPbCl3 NCs, trioctylphosphine (1 mL) was additionally needed. CsPbCl3 or CsPbBr3 NCs were synthesized by quickly injecting Cs-oleate solution (0.4 ml) into lead precursor under N2 atmosphere at 150 ºC, and then the mixture was cooled by ice-water bath. Synthesis

and

purification

of

MnII-doped

CsPb(Cl/Br)3

nanocrystals

(Mn:CsPb(Cl/Br)3 NCs). Mn:CsPb(Cl/Br)3 NCs were obtained by anion exchange. The colloidal solution of CsPbBr3 NCs was dropwise add into that of Mn0.078:CsPb0.922Cl3 NCs under atmospheric stirring until the apparent fluorescence color of solution turn violet. To promote the exchange equilibrium of halogen anions within a short time, solution was moderatly heated for a while. The purification treating was the same as that of Mn:CsPbCl3 NCs. OAm washing of Mn:CsPbCl3 NCs. Mn:CsPbCl3 NCs were washed by the diluted OAm to remove some near-surface MnII dopants. Typically, OAm (0.4 mL) was added into 10 mL of the homogenous colloidal solution of Mn0.175:CsPb0.825Cl3 NCs (1 mg/mL). After being stirring for 5 minutes, the PNCs in solution were purificated and then the products were collected. HCl vapor treating of Mn:CsPb(Cl/Br)3 NCs. Testing film of Mn:CsPb(Cl/Br)3 NCs was placed above an open test tube containing the concentrated hydrochloric acid. Such device was


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enclosed in an inverted beaker, and then the film was exposed to the HCl vapor for 20 minutes. The whole operation was carried out in a fume hood with necessary protective measures. Oxygen sensing based on perovskite testing films. The perovskite films were deposited onto quartzs substrates by drop-coating method using homogenous colloidal solution (1 mg/mL) of different PNCs. During the gaseous O2 detection, two sets of gas flowmeter (Alicat Scientific, USA) acted as controllers for O2 fraction (%). N2/O2 gas mixtures blew the films for one minute to equilibrate the concentration of O2, and then the PL emission spectra and PL decay curves were recorded. The response time and reversibility was investigated during 10 cycles of interswitching between pure O2 and pure N2. Photochemical stability at atmospheric condition was investigated under continuous UV irradiation for 60 minutes (every 10 minutes a record). Such film was then temporarily blown by pure N2 for a minute before one more record in air. Above experiments are conducted under constant temperature. RESULTS AND DISCUSSION Mn:CsPbCl3 NCs were synthesized via the heat-up strategy (Figure 1a). With the PbII : MnII feed ratio of 1 : 9, the reactants were heated up to 100 °C to obtain the products, Mn0.078:CsPb0.922Cl3 NCs, where Mnx:CsPb1-xCl3 represented the molar fraction x of MnII in the molar sum of PbII and MnII according to the chemical composition. TEM and HRTEM images (Figure 1b) show that Mn0.078:CsPb0.922Cl3 NCs present cubic morphology with an average size of 12 nm. Their inter-planar distance of 3.9 Å (inset of Figure 1b) well matches either the (110) planes of the cubic phase (PDF#84-0438) or the (101) planes of tetragonal phase (PDF#180366).37,

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As a function of MnII incorporation, the line broadening of XRD patterns peaks

makes it hard to distinguish the exact crystalline phase, but PNCs preserve good structure (Figure 1c). The EPR spectrum (Figure 1d) shows a sextet hyperfine splitting spectrum with


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coupling constant of 87 G and explains the octahedral ligand field environment of substituted MnII (S=2/5) in the PNCs.36, 42 Furthermore, the mapping images verify the distribution of Cs, Pb, Cl and Mn elements over the entire PNCs (Figure S1). Therefore, MnII ions were successfully incorporated into the CsPbCl3 host without big structural changes. Because doping MnII ions into host NCs provides a new direction for exciton energy transfer, the dual-emission PL spectrum deriving from single exciton band edge absorption implies the presence of intraparticle HDET in PNCs (Figure 1e).38 On this basis, the oxygensensitive PL emission of Mn:CsPbCl3 NCs was investigated using the testing films. Comparing the PL spectra between the film and the hexane solution of Mn:CsPbCl3 NCs (Figure S2), the film has no essential influence on the PL spectra of PNCs. To acquire the O2-sensitive emission spectra of PNCs, the atmosphere composition above the testing films changes from pure N2 to pure O2. The single exciton emission of undoped CsPbCl3 film consequently experiences a decreased PL intensity (13% quenching) and a shortened lifetime (Figure 1f and Figure S3), which is attributed to the dominant photoexcited electron capture. However, for Mn:CsPbCl3 NCs, except for the limited evolution of exciton emission intensity (7% brightening) stemming from similar multi-factor counterbalance above, we notice an relatively obvious intensity decline (27%) of MnII emission with peak blue shift (Figure 1g), which is tentatively ascribed to O2 and will be discussed in the following experiments.


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Figure 1. (a) Schematic representation of heat-up syntheses. (b) TEM and HRTEM images (inset) of Mn:CsPbCl3 NCs. (c) XRD diffraction patterns of Mn:CsPbCl3 NCs and CsPbCl3 NCs. (d) Room temperature EPR spectrum of Mn:CsPbCl3 NCs at 9.84 GHz. (e) Absorption and fluorescence emission spectra of Mn:CsPbCl3 NCs and CsPbCl3 NCs. PL spectra of the testing films under 100% N2, 21% O2, and 100% O2 for (f) the CsPbCl3 NCs and (g) the Mn:CsPbCl3 NCs. Excitation wavelength: 365 nm.


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To gain a comprehensive understanding of the O2-induced PL quenching of MnII emission, we first studied PNCs with tunable MnII incorporation. Reactant feed ratios of PbII to MnII were tuned from 1 : 3, 1 : 6 to 1 : 9 with a fixed synthesis temperature of 100 °C, corresponding to Mn0.025:CsPb0.975Cl3, Mn0.036:CsPb0.964Cl3 and Mn0.078:CsPb0.922Cl3, respectively. TEM images (Figure 2a) shows that different PNCs keep cubic morphology, but more chlorine precursors enhance the nucleation number and favor the MnII incorporation,32 which simultaneously causes a slight size shrinkage of PNCs. A small blue shift of the band edge absorption peaks (Figure S4a) echoes the decreased crystal size calculated from the Scherrer equation (Table S1). When more PbII ions in octahedral ligand field are substituted by MnII ions with smaller six-coordinate crystal ionic radius,35 the XRD peaks slightly move to higher angles by an enhanced lattice contraction (Figure S4b),21, 35 and the crystallinity of PNCs decreases a little (Table S1). More importantly, the HDET process in PNCs is facilitated. Raising doping ratios (from 2.5% to 7.8%) increases the normalized intensity ratio (IMn/Ihost) (Figure 2b). The exciton recombination process is accelerated (from 9.6 ns to 5.9 ns) (Figure 2c), and the MnII emission with longer decay time (from 0.5 ms to 1.4 ms) can be observed (Figure 2d). 31, 44 Thus, the moderated high feed ratio of MnII promotes the ions incorporation and HDET process.


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Figure 2. (a) TEM images, (b) fluorescence emission spectra, (c) exciton-related time-resolved PL decay curves (detected at 410 nm) and (d) MnII-related time-resolved PL decay curves (detected at 586 nm) of Mn:CsPbCl3 NCs that synthesized under 100 °C with different PbII : MnII feed ratios from 1 : 3, 1 : 6 to 1 : 9. Excitation wavelength: 365 nm. On this basis, we conducted O2 sensing experiments using films of Mn:CsPbCl3 NCs with incremental doping ratios. Figure 3a-c show that when the atmospheric O2 percentage (%) increases from 0% to 100%, the MnII-related PL intensity gradually decreases (when the intensity maximum of host emission is normalized as reference). This process is reversible after removing O2 by N2, and there is no change of the spectral profile except for a reversible blue shift of MnII emission peak. As the doping ratios of MnII ions raise from 2.5% to 7.8%, the variation of host emission is limited after O2 treating, but the PL dimming of MnII emission is more pronounced, which manifests as the increasing quenching degree from 9% to 27% (when


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MnII-related intensity maximum under pure N2 condition is normalized as reference). Changing doping ratios here essentially favors the interaction between O2 and the luminous MnII dopants, and then the higher O2 sensitivity can be observed. This estimation can be confirmed from the time-resolved PL decay of MnII emission (Figure 3d). O2 speeds up the fast decay part of the MnII-related lifetime curve but hardly affects the slow decay part from the intrisic d-d transitions, implying the quenching process caused by the surface state. These results indicate that O2 directly affects the luminous MnII dopants in PNCs. At the same time, O2 seems to not obviously influence the exciton emission and lifetime (Figure 3c and Figure S5). Because apparent exciton emission is the comprehensive result of radiative transition and HDET, it is presumably the decrease of luminous MnII dopants that reversely suppresses the HDET and thereby promotes the exciton recombination in host PNCs. To elucidate the exact role of luminous MnII dopants, we prepared the testing film of Mn:CsPb(Cl/Br)3 NCs with violet fluorescence. Comparing with Mn:CsPbCl3 NCs, the energy difference between the band edge of CsPbBr3 host and the MnII-related 4T1→6A1 transitions is smaller35, so Mn:CsPb(Cl/Br)3 NCs have a weaker HDET for the limited luminous MnII. As the surrounding condition of Mn:CsPb(Cl/Br)3 film changes from 100% N2 to 100% O2, the PL intensity of host emission and MnII emission decreases by 12% and 5%, respectively (Figure 3e). However, if the same testing film is exposed to HCl vapor, HDET can be promoted by in-suit anion exchange from Br- to Cl- without loss of MnII ions, so an apparent peak blue shift, the decreased PL intensity and a lower sensitivity to O2 (4% PL dimming) can be seen from the host emission. More importantly, both the PL brightening and lifetime extension of the MnII emission clarify that the improved HDET actually increases the number of luminous MnII dopants (Figure


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3e and 3f). As a result, the quenching degree of MnII emission under pure O2 indeed increases to 14%. So it is concluded that luminous MnII dopants are the oxygen-sensitive sites in PNCs.

Figure 3. PL spectra of the testing films under 100% N2, 21% O2, and 100% O2 for (a) the Mn0.025:CsPb0.975Cl3 NCs, (b) the Mn0.036:CsPb0.964Cl3 NCs and (c) the Mn0.078:CsPb0.922Cl3 NCs. (d) The Mn-related time-resolved PL decay of testing films under 100% N2 and 100% O2 for Mn0.078:CsPb0.922Cl3 NCs (excited at 365 nm, detected at 586 nm). (e) PL spectra under 100% N2, 21% O2, and 100% O2, (f) the Mn-related time-resolved PL decay under 100% N2 and 100% O2 for Mn:CsPb(Cl/Br)3 film that before or after HCl vapour treating. (Excitated at 365 nm). From the PL spectra above, it is noticed that pure O2 is not enough for the complete quenching of MnII emission. The higher sensitivity to low O2 concentration (less than 21%) probably points to the role of the near-surface MnII dopants in PNCs. Furthermore, chemical environment can influence the 4T1→6A1 state splitting of MnII ions.41 As reported in MnII-doped CdS NCs,45 surface dopants with more ligand-field interactions gives rise to the red shift. Analogously, in comparison to the constant peak position of host emission, the reversible peak


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blue shift of MnII emission is observed after exposured to O2, which probably ssuggests the strength change of ligand field of the near-surface MnII dopants. In view of the significance of temperature to dopants diffusion in semiconductor NCs,43, 46 we changed the synthesis temperatures from 100 °C, 120 °C to 140 °C with fixed PbII : MnII feed ratio of 1 : 9, and obtained the PNCs varying from Mn0.078:CsPb0.922Cl3, Mn0.102:CsPb0.898Cl3 to Mn0.175:CsPb0.825Cl3. Highly ionized perovskite makes the thermal-driving doping easier. As temperatures raise, PNCs reveal the unaffected morphology (Figure 4a) and band edge absorption (Figure S6a). The crystalline phase is also preserved, even if doping MnII ions promotes the lattice contraction and the decrease of crystallinity (Figure S6b and Table S1). Owing to the facilitated MnII incorporation under higher temperature, the normalized PL intensity ratio (IMn/Ihost) shows an increasing trend with the peak red shift of MnII emission (Figure 4b). The facilitated HDET process is manifested as the shorter lifetime of exciton emission (from 5.9 ns to 3.7 ns) (Figure 4c) and the longer lifetime of MnII emission (from 1.4 ms to 1.5 ms) (Figure 4d).31 With the further increase of doping ratio under 140 °C, a slight PL dimming and the lifetime decay of MnII emission (from 1.6 ms to 1.5 ms) reflect the amplified MnII ion-pairing exchange interaction,33, 40-41 but this also indicates the presence of high doping concentration and thereby abundant near-surface MnII dopants in host PNCs.


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Figure 4. (a) TEM images, (b) fluorescence emission spectra, (c) exciton-related time-resolved PL decay curves (detected at 410 nm) and (d) MnII-related time-resolved PL decay curves (detected at 586 nm) of Mn:CsPbCl3 NCs that synthesized under different temperatures with fixed PbII : MnII feed ratio of 1 : 9. Excitation wavelength: 365 nm. To confirm that the near-surface MnII dopants are the preferred sites for O2, we performed the sensing experiments using films of Mn:CsPbCl3 NCs with different synthesis temperatures from100 °C to 140 °C. When the N2 atmosphere gradually turns into pure O2, the MnII emissions of PNCs with higher synthesis temperatures have the rising trend of quenching degrees from 27% to 53% (Figure 5a-c). In contrast to the PL quenching of PNCs synthesized under 100 °C (Figure 3d), their counterparts prepared under 140 °C show a greater lifetime decline concretely from the fast part of PL decay curve, indicating an accelerated decay dynamic to O2 (Figure 5d).


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As expected, rising temperatures benefits the diffusion of MnII dopants and HDET process in PNCs, correspondingly leading to higher sensitivity to O2. Because O2 has virtually no effect on the morphology, crystalline structure or the surface ligands of the PNCs (Figure S7 and S8), it is probably the moderately higher concentration of near-surface MnII dopants that increases the opportunity to interact with O2. This idea was corroborated from the changed EPR signals of Mn:CsPbCl3 NCs in O2 (Figure S9). Compared to the EPR spectra in N2, the presence of O2 weakens the sextet hyperfine splitting signals of MnII ions in the octahedral ligand field in PNCs, reflecting the disturbed chemical environment of MnII dopants. Removing O2 by N2 results in the recovery of EPR signals, which means the disturbance to ligand field is temporary and reversible, which echoes the reversible blue shift of MnII emission peak in O2. Moreover, Mn0.175:CsPb0.825Cl3 NCs with higher doping ratio and more near-surface MnII dopants correspondingly show greater signal fluctuation than that of Mn0.078:CsPb0.922Cl3 NCs to O2. These results imply that O2 has greater impact on the ligand field of accessible near-surface MnII dopants. We further identified the role of near-surface MnII dopants through OAm washing process, which can remove some nearsurface MnII dopants during the displacment of surface ligands and reduce the doping ratios from 17.5% to 9.4%. Consequently, partial decrease in MnII-related PL intensity is found as shown in Figure 5e. Less near-surface MnII dopants reduced the quenching degree (41%) to pure O2 compared to that before OAm washing (Figure 5f). Results above match with our opinion that O2 mainly affects the properties of luminous MnII dopants distributed in the near-surface portion of PNCs.


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Figure 5. PL spectra of the testing films under 100% N2, 21% O2, and 100% O2 for (a) the Mn0.078:CsPb0.922Cl3 NCs, (b) the Mn0.102:CsPb0.898Cl3 NCs and (c) the Mn0.175:CsPb0.825Cl3 NCs. (d) The Mn-related time-resolved PL decay of testing films under 100% N2 and 100% O2 for Mn0.175:CsPb0.825Cl3 NCs (excited at 365 nm, detected at 586 nm). (e) PL spectra of Mn:CsPbCl3 NCs that before (Mn0.175:CsPb0.825Cl3) and after (Mn0.094:CsPb0.906Cl3) being washed by OAm. (f) PL spectra of the testing film under 100% N2, 21% O2 and 100% O2 for Mn0.094:CsPb0.906Cl3 NCs. (Excitated at 365 nm). Therefore, the intrinsic sensing mechanism is outlined in Scheme 1. O2 can directly absorb on the surface of Mn:CsPbCl3 NCs and influence their optical performance by (i) disturbing the exciton recombination of CsPbCl3 emission and (ii) temporarily deactivating the luminous MnII dopants. For role (i), O2 directly extract photoexcited electrons from the conduction band, accompanying with the hole-traps passivation. The competition between these two factors results in an overall limited sensitivity of host PL emission to O2. More importantly, for role (ii), O2 can reversibly affect the ligand field of accessible near-surface MnII dopants in PNCs by direct


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interaction. This on one aspect causes the performance degradation of MnII emission including PL intensity and lifetime. For another aspect, after contrasting the O2-induced lifetime change of exciton emission in CsPbCl3 NCs (Figure S3) with that of Mn:CsPbCl3 NCs (Figure S5 and S10), the temporary disturbance of the ligand field of luminous MnII dopants probably suppresses the HDET process. This reduces the excitonic energy dissipation in perovskite system, which instead promotes the exciton recombination of host NCs.

Scheme 1. Schematic representation of the interaction mechanism between O2 and Mn:CsPbCl3 NCs. See the dawn of the inherent sensing capability of Mn:CsPbCl3 NCs to O2, the roomtemperature phosphorescence detection was performed by using the film of Mn0.175:CsPb0.825Cl3 NCs. As shown in Figure 6a, the MnII-related phosphorescence spectra at the specific O2 percentage (%) are clearly observed. As the O2 fraction increases, this phosphorescence begins to dim and especially shows a large sensitivity to the low O2 concentrations. Figure 6b shows the signal changes in a loop (from 0% to 100% and to 0% O2), and the fitting of the phosphorescence intensity ratio (I0/I) vs. O2 percentage was calculated by the Stern-Volmer equation: ⁄ O 1

(1)


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where I0 and I, respectively, represent the maximum phosphorescence intensities in the absence and presence of specific concentrations of O2 (expressed as volume % units) is the fraction of oxygen above the film, and KSV is the Stern-Volmer constant. The fitting curves mostly overlap due to the reversible phosphorescence recovery procedure with the increase of PL quantum yield from 0.17 (100% O2) to 0.37 (0% O2). As long as the testing film is exposed to an atmosphere having percentage of O2 less than 12% (Figure 6c), a linear Stern-Volmer plot is obtained that can be described by KSV = 0.0658%[O2]−1 (R2 = 0.9997). Corresponding, the time-resolved PL decay in the linear region (Figure S11) are in agreement with the accelerated decay dynamic of the fast decay part of lifetime to the increasing O2 concentrations. In addition, the sensing reversibility was demonstrated in ten repeated cycles without obvious loss in performance (Figure 6d). As shown in Figure 6e, we evaluated the response and recovery time. In the presence of O2, 97% of the phosphorescence quenching degree is achieved within 5 s. If O2 is removed, 84% of the phosphorescence quenching degree recovers within 10 s, this followed by a second and slow phosphorescence recovery process. Combining the high sensitivity of MnII emission to low O2 condition, we believe that the instantaneous phosphorescence dimming is caused by the direct contact between O2 and near-surface MnII dopants, but the desorption of O2 may be not so rapid as the surface adsorption process.12 We further study the photostability in air (Figure 6f). Although the phosphorescence intensity drops by 6% after one hour, but the constant peak position of MnII emission rules out the possibility of permanent surface oxidation for the dopants.47 If we temporarily blow the film with pure N2 again to accelerate the removal of absorbed O2, the phosphorescence in air recovers to the initial intensity, which excludes the irreversible loss of MnII dopants during limited photobleaching. In summary, different from (i) the functionalized NCs with foreign phosphorescent moleculers and


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(ii) the semiconductor NCs with O2-sensitive exciton emission (about ns-scale lifetime), Mn:CsPbCl3 is the first example with intrinsic phosphorescent sensing centers for O2 (Table S2). Further effort needs to be devoted to improve the sensitivity, but it has laid a foundation to feasible phosphorescence sensing of O2 using Mn:CsPbCl3 NCs.

Figure 6. Sensing responses of the Mn0.175:CsPb0.825Cl3 film to O2. (a) Phosphorescence spectra under different O2 fractions (%); (b) The first-order reaction kinetics curves of the maximum phosphorescence intensities under different O2 fractions (%); (c) Stern-Volmer plot under the O2 fractions between 0 and 12%; (d) Reversibility test under the alternating exposure to 100% O2 or 100% N2 (detected at 586 nm); (e) The response time curve within one cycle test. (f) Photostability test in air condition. (Excitated at 365 nm). CONCLUSIONS We have investigated for the first time the effect of O2 on the luminescence of Mn:CsPbCl3 NCs and demonstrated a possible mechanism about the inherent O2 sensing capability. By


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adjusting the amount and distribution of MnII dopants, as well as the degree of HDET process in PNCs,

we conclude that the near-surface MnII dopants are the sensitive sites whose ligand field

can be temporarily disturbed by O2 and thereby influences the MnII emission (4T1→6A1). The sensing film of PNCs shows the fast and reversible phosphorescence quenching degree of 53%, and the good linear correlation of phosphorescence intensity in the 0-12% O2 concentration range. Consequently, it is enlightening to broaden the potential of Mn:CsPbCl3 NCs in phosphorescence sensing of even rather low O2 conditions in environment application, and such capability is likely to be extend to more semiconductor doped-nanocrystals with phosphorescence emission stemming from HDET.

ASSOCIATED CONTENT Supporting Information. The supporting Information is available free of charge on the ACS publication website.

Additional XRD diffraction patterns, absorption spectra and element mapping images of the Mn:CsPbCl3 NCs. PL spectra of the testing film and the hexane solution of Mn:CsPbCl3 NCs. The effect of O2 on TEM image, XRD diffraction patterns, 1H NMR spectra, FTIR spectra, EPR spectra and the exciton-related time-resolved PL decay curves of Mn:CsPbCl3 NCs. The Mnrelated time-resolved PL decay under different O2 fractions (0-12%). A table summarized the crystal size and crystallinity of Mn:CsPbCl3 NCs prepared under different conditions. A table comparing some representative semiconductor NC-based PLQPs for O2. (PDF)

AUTHOR INFORMATION Corresponding Author * E-mail: [email protected]


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Author Contributions This experiment was conducted through contributions of all authors. F. Lin and F. Li contributed equally to the manuscript. Other authors have given approval to the final version of this paper.

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work was financially supported by National Natural Science Foundation of China (No. 21675133).

REFERENCES (1) Wang, X.-d.; Wolfbeis, O. S. Optical Methods for Sensing and Imaging Oxygen: Materials, Spectroscopies and Applications. Chem. Soc. Rev. 2014, 43, 3666–3761. (2) Wolfbeis, O. S. Luminescent Sensing and Imaging of Oxygen: Fierce Competition to the Clark Electrode. Bioessays 2015, 37, 921–928. (3) J. N. Demas; E. W. Harris; McBride, R. P. Energy Transfer from Luminescent Transition Metal Complexes to Oxygen. J. Am. Chem. Soc. 1977, 99, 3547–3551. (4) Wang, X.-d.; Chen, X.; Xie, Z.-x.; Wang, X.-r. Reversible Optical Sensor Strip for Oxygen. Angew. Chem. Int. Ed. 2008, 47, 7450–7453.


23


Page 24 of 30

(5) Nagl, S.; Baleizao, C.; Borisov, S. M.; Schaferling, M.; Berberan-Santos, M. N.; Wolfbeis, O. S. Optical Sensing and Imaging of Trace Oxygen with Record Response. Angew. Chem., Int. Ed. 2007, 46, 2317–2319. (6) Xu, R.; Wang, Y.; Duan, X.; Lu, K.; Micheroni, D.; Hu, A.; Lin, W. Nanoscale Metal– Organic Frameworks for Ratiometric Oxygen Sensing in Live Cells. J. Am. Chem. Soc. 2016, 138, 2158–2161. (7) Wu, P.; Yan, X. P. Doped Quantum Dots for Chemo/Biosensing and Bioimaging. Chem. Soc. Rev. 2013, 42, 5489–5521. (8) McLaurin, E. J.; Greytak, A. B.; Bawendi, M. G.; Nocera, D. G. Two-Photon Absorbing Nanocrystal Sensors for Ratiometric Detection of Oxygen. J. Am. Chem. Soc. 2009, 131, 12994– 13001. (9) Park, J.; Lee, J.; Kwag, J.; Baek, Y.; Kim, B.; Yoon, C. J.; Bok, S.; Cho, S.-H.; Kim, K. H.; Ahn, G.-O.; Kim, S. Quantum Dots in an Amphiphilic Polyethyleneimine Derivative Platform for Cellular Labeling, Targeting, Gene Delivery, and Ratiometric Oxygen Sensing. ACS nano 2015, 9, 6511–6521. (10) Lemon, C. M.; Karnas, E.; Han, X.; Bruns, O. T.; Kempa, T. J.; Fukumura, D.; Bawendi, M. G.; Jain, R. K.; Duda, D. G.; Nocera, D. G. Micelle-Encapsulated Quantum Dot-Porphyrin Assemblies as in Vivo Two-Photon Oxygen Sensors. J. Am. Chem. Soc. 2015, 137, 9832–9842. (11) Amelia, M.; Lavie-Cambot, A.; McClenaghan, N. D.; Credi, A. A Ratiometric Luminescent Oxygen Sensor Based on a Chemically Functionalized Quantum Dot. Chem. Commun. 2011, 47, 325–327.


24

Page 25 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(12) Lau, P. C.; Norwood, R. A.; Mansuripur, M.; Peyghambarian, N. An Effective and Simple Oxygen

Nanosensor

Made

from

MPA-Capped

Water

Soluble

CdTe

Nanocrystals.

Nanotechnology 2013, 24, 015501. (13) Lorenzon, M.; Pinchetti, V.; Bruni, F.; Bae, W. K.; Meinardi, F.; Klimov, V. I.; Brovelli, S. Single-Particle Ratiometric Pressure Sensing Based on "Double-Sensor" Colloidal Nanocrystals. Nano Lett. 2017, 17, 1071–1081. (14) Lorenzon, M.; Sortino, L.; Akkerman, Q.; Accornero, S.; Pedrini, J.; Prato, M.; Pinchetti, V.; Meinardi, F.; Manna, L.; Brovelli, S. Role of Nonradiative Defects and Environmental Oxygen on Exciton Recombination Processes in CsPbBr3 Perovskite Nanocrystals. Nano Lett. 2017, 17, 3844–3853. (15) Yakunin, S.; Protesescu, L.; Krieg, F.; Bodnarchuk, M. I.; Nedelcu, G.; Humer, M.; De Luca, G.; Fiebig, M.; Heiss, W.; Kovalenko, M. V. Low-Threshold Amplified Spontaneous Emission and Lasing from Colloidal Nanocrystals of Caesium Lead Halide Perovskites. Nat. Commun. 2015, 6, 8056. (16) Leijtens, T.; Eperon, G. E.; Noel, N. K.; Habisreutinger, S. N.; Petrozza, A.; Snaith, H. J. Stability of Metal Halide Perovskite Solar Cells. Adv. Energy Mater. 2015, 5, 1500963. (17) Li, J.; Xu, L.; Wang, T.; Song, J.; Chen, J.; Xue, J.; Dong, Y.; Cai, B.; Shan, Q.; Han, B.; Zeng, H. 50-Fold EQE Improvement up to 6.27% of Solution-Processed All-Inorganic Perovskite CsPbBr3 QLEDs via Surface Ligand Density Control. Adv. Mater. 2017, 29, 1603885. (18) Li, X.; Yu, D.; Chen, J.; Wang, Y.; Cao, F.; Wei, Y.; Wu, Y.; Wang, L.; Zhu, Y.; Sun, Z.; Ji, J.; Shen, Y.; Sun, H.; Zeng, H. Constructing Fast Carrier Tracks into Flexible Perovskite Photodetectors To Greatly Improve Responsivity. ACS nano 2017, 11, 2015–2023.


25


Page 26 of 30

(19) Kovalenko, M. V.; Protesescu, L.; Bodnarchuk, M. I. Properties and potential optoelectronic applications of lead halide perovskite nanocrystals. Science 2017, 358, 745–750. (20) Amgar, D.; Aharon, S.; Etgar, L. Inorganic and Hybrid Organo-Metal Perovskite Nanostructures: Synthesis, Properties, and Applications. Adv. Funct. Mater. 2016, 26, 8576– 8593. (21) Travis, W.; Glover, E. N. K.; Bronstein, H.; Scanlon, D. O.; Palgrave, R. G. On the Application of the Tolerance Factor to Inorganic and Hybrid Halide Perovskites: A Revised System. Chem. Sci. 2016, 7, 4548–4556. (22) Li, X.; Cao, F.; Yu, D.; Chen, J.; Sun, Z.; Shen, Y.; Zhu, Y.; Wang, L.; Wei, Y.; Wu, Y.; Zeng, H. All Inorganic Halide Perovskites Nanosystem: Synthesis, Structural Features, Optical Properties and Optoelectronic Applications. Small 2017, 13, 1603996. (23) Liu, H.; Wu, Z.; Gao, H.; Shao, J.; Zou, H.; Yao, D.; Liu, Y.; Zhang, H.; Yang, B. One-Step Preparation of Cesium Lead Halide CsPbX3 (X = Cl, Br, and I) Perovskite Nanocrystals by Microwave Irradiation. ACS Appl. Mater. Interfaces 2017, 9, 42919–42927. (24) Xu, W.; Li, F.; Cai, Z.; Wang, Y.; Luo, F.; Chen, X. An ultrasensitive and reversible fluorescence sensor of humidity using perovskite CH3NH3PbBr3. J. Mater. Chem. C 2016, 4, 9651–9655. (25) Niu, Y.; Zhang, F.; Bai, Z.; Dong, Y.; Yang, J.; Liu, R.; Zou, B.; Li, J.; Zhong, H. Aggregation-Induced Emission Features of Organometal Halide Perovskites and Their Fluorescence Probe Applications. Adv. Opt. Mater. 2015, 3, 112–119. (26) Chen, X.; Hu, H.; Xia, Z.; Gao, W.; Gou, W.; Qu, Y.; Ma, Y. CsPbBr3 perovskite nanocrystals as highly selective and sensitive spectrochemical probes for gaseous HCl detection. J. Mater. Chem. C 2017, 5, 309–313.


26

Page 27 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(27) Sasmal, S.; Sinha, A.; Donnadieu, B.; Pala, R. G. S.; Sivakumar, S.; Valiyaveettil, S. Volatility and Chain Length Interplay of Primary Amines: Mechanistic Investigation on the Stability and Reversibility of Ammonia-Responsive Hybrid Perovskites. ACS Appl. Mater. Interfaces 2018, 10, 6711–6718. (28) Tian, Y.; Merdasa, A.; Unger, E.; Abdellah, M.; Zheng, K.; McKibbin, S.; Mikkelsen, A.; Pullerits, T.; Yartsev, A.; Sundstrom, V.; Scheblykin, I. G. Enhanced Organo-Metal Halide Perovskite Photoluminescence from Nanosized Defect-Free Crystallites and Emitting Sites. J. Phys. Chem. Lett. 2015, 6, 4171–4177. (29) Meggiolaro, D.; Mosconi, E.; De Angelis, F. Mechanism of Reversible Trap Passivation by Molecular Oxygen in Lead-Halide Perovskites. ACS Energy Lett. 2017, 2794–2798. (30) Lorenzon, M.; Christodoulou, S.; Vaccaro, G.; Pedrini, J.; Meinardi, F.; Moreels, I.; Brovelli, S. Reversed Oxygen Sensing Using Colloidal Quantum Wells Towards Highly Emissive Photoresponsive Varnishes. Nat. Commun. 2015, 6, 6434. (31) Lin, C. C.; Xu, K. Y.; Wang, D.; Meijerink, A. Luminescent Manganese-Doped CsPbCl3 Perovskite Quantum Dots. Sci. Rep. 2017, 7, 45906. (32) Das Adhikari, S.; Dutta, S. K.; Dutta, A.; Guria, A. K.; Pradhan, N. Chemically Tailoring the Dopant Emission in Manganese-Doped CsPbCl3 Perovskite Nanocrystals. Angew. Chem. Int. Ed. 2017, 129, 8872–8876. (33) Yuan, X.; Ji, S.; De Siena, M. C.; Fei, L.; Zhao, Z.; Wang, Y.; Li, H.; Zhao, J.; Gamelin, D. R. Photoluminescence Temperature Dependence, Dynamics, and Quantum Efficiencies in Mn2+Doped CsPbCl3 Perovskite Nanocrystals with Varied Dopant Concentration. Chem. Mater. 2017, 29, 8003–8011.


27


Page 28 of 30

(34) Xu, W.; Li, F.; Lin, F.; Chen, Y.; Cai, Z.; Wang, Y.; Chen, X. Synthesis of CsPbCl3-Mn Nanocrystals via Cation Exchange. Adv. Opt. Mater. 2017, 5, 1700520. (35) Liu, W.; Lin, Q.; Li, H.; Wu, K.; Robel, I.; Pietryga, J. M.; Klimov, V. I. Mn2+-Doped Lead Halide Perovskite Nanocrystals with Dual-Color Emission Controlled by Halide Content. J. Am. Chem. Soc. 2016, 138, 14954–14961. (36) Parobek, D.; Roman, B. J.; Dong, Y.; Jin, H.; Lee, E.; Sheldon, M.; Son, D. H. Exciton-toDopant Energy Transfer in Mn-Doped Cesium Lead Halide Perovskite Nanocrystals. Nano Lett. 2016, 16, 7376–7380. (37) Mir, W. J.; Jagadeeswararao, M.; Das, S.; Nag, A. Colloidal Mn-Doped Cesium Lead Halide Perovskite Nanoplatelets. ACS Energy Letters 2017, 2, 537–543. (38) Guria, A. K.; Dutta, S. K.; Adhikari, S. D.; Pradhan, N. Doping Mn2+ in Lead Halide Perovskite Nanocrystals: Successes and Challenges. ACS Energy Lett. 2017, 2, 1014–1021. (39) Beaulac, R.; Archer, P. I.; Ochsenbein, S. T.; Gamelin, D. R. Mn2+-Doped CdSe Quantum Dots: New Inorganic Materials for Spin-Electronics and Spin-Photonics. Adv. Funct. Mater. 2008, 18, 3873–3891. (40) Pu, C.; Ma, J.; Qin, H.; Yan, M.; Fu, T.; Niu, Y.; Yang, X.; Huang, Y.; Zhao, F.; Peng, X. Doped Semiconductor-Nanocrystal Emitters with Optimal Photoluminescence Decay Dynamics in Microsecond to Millisecond Range: Synthesis and Applications. ACS Cent. Sci. 2016, 2, 32– 39. (41) Pradhan, N. Red-Tuned Mn d-d Emission in Doped Semiconductor Nanocrystals. Chemphyschem 2016, 17, 1087–1094.


28

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(42) Zou, S.; Liu, Y.; Li, J.; Liu, C.; Feng, R.; Jiang, F.; Li, Y.; Song, J.; Zeng, H.; Hong, M.; Chen, X. Stabilizing Cesium Lead Halide Perovskite Lattice through Mn (II)-Substitution for Air-Stable Light-Emitting Diodes. J. Am. Chem. Soc. 2017, 139, 11443–11450. (43) Liu, H.; Wu, Z.; Shao, J.; Yao, D.; Gao, H.; Liu, Y.; Yu, W.; Zhang, H.; Yang, B. CsPbxMn1-xCl3 Perovskite Quantum Dots with High Mn Substitution Ratio. ACS nano 2017, 11, 2239–2247. (44) Wang, Q.; Zhang, X.; Jin, Z.; Zhang, J.; Gao, Z.; Li, Y.; Liu, S. F. Energy-Down-Shift CsPbCl:Mn Quantum Dots for Boosting the Efficiency and Stability of Perovskite Solar Cells. Acs Energy Lett. 2017, 2, 1479–1486. (45) A.Nag; R. Cherian; P.Mahadevan; A. V. Gopal; A. Hazarika; A. Mohan; A. S. Vengurlekar; D.D.Sarma. Size-Dependent Tuning of Mn2+ d Emission in Mn2+-Doped CdS Nanocrystals: Bulk vs Surface. J. Phys. Chem.C 2010, 114, 18323–18329. (46) Huang, G.; Wang, C.; Xu, S.; Zong, S.; Lu, J.; Wang, Z.; Lu, C.; Cui, Y. Postsynthetic Doping of MnCl2 Molecules into Preformed CsPbBr3 Perovskite Nanocrystals via a Halide Exchange-Driven Cation Exchange. Adv. Mater. 2017, 29, 1700095. (47) Duncan, T. V.; Polanco, M. A. M.; Kim, Y.; Park, S.-J. Improving the Quantum Yields of Semiconductor Quantum Dots through Photoenhancement Assisted by Reducing Agents. J. Phys. Chem. C 2009, 113, 7561–7566.


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Table of Contents Graphic


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MnII-Doped Cesium Lead Chloride Perovskite Nanocrystals

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