Dimensionality and Interface Engineering of 2D Homologous

Letter pubs.acs.org/JPCL

Dimensionality and Interface Engineering of 2D Homologous Perovskites for Boosted Charge-Carrier Transport and Photodetection Performances Dejian Yu,† Fei Cao,† Yalong Shen,† Xuhai Liu, Ying Zhu, and Haibo Zeng* Institute of Optoelectronics & Nanimaterials, MIIT Key Laboratory of Advanced Display Material and Devices, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

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S Supporting Information *

ABSTRACT: Two-dimensional (2D) homologous halide perovskite (HP) microcrystallines have emerged as a promising alternative light-sensitive material; however, the undesirable quantum confinement effect and severe interfacial charge-carrier scattering still hamper their applications in photodetectors (PDs). Here we propose a novel postsynthetic treatment to simultaneously solve both problems. 2D (OA)2FAn−1PbnBr3n+1 (OA and FA represent octadecylamine and formamidine) microplatelet film was immersed in solution containing FA+, leading to improvements in two aspects. First, the dimensionality of 2D HPs was increased through an exchange reaction between OA+ and FA+, which meliorates the quantum confinement effect and facilitates the separation of electrons and holes; second, the free-standing 2D HP microcrystallines were fused for promoted interdomain charge-carrier transport. The treated PDs achieved a 3600 and 4200% increase in external quantum yield and responsivity up to 7100% and 32 A/W, respectively, and the rise/decay time was shortened by two orders of magnitude to 0.25/1.45 ms.

H

such requirements. For 2D homologous HPs, basically a chemical formula of R2An−1PbnX3n+1 is adopted,37 where n is the number of octahedra layers and R represents long-chain ammonium that cannot fit the cavity within the octahedra framework. Because of the 2D structural characteristic, large edge size up to several micrometers can be easily obtained,38−40 which is much larger than the domain size in a polycrystalline film and therefore increases charge-carrier mean-free path and reduces hopping. Besides, the 2D HPs naturally possess uniaxial lattice orientation,41,42 which recently was reported to significantly promote charge-carrier transport and enhance photovoltaic performances.29,43 Moreover, 2D HPs own suppressed defect concentration and enhanced stability compared with other counterparts.44,45 Therefore, the 2D HPs microcrystallines hold great promise for PDs applications. For example, Tan et al. fabricated PDs on individual 2D (C4H9NH3)2PbBr4 crystal with ultrahigh responsivity up to 2100 A/W.38 However, when these 2D HPs microcrystallines are assembled into film, two problems still significantly hamper the performances of PDs. First, electrons and holes usually suffer from strong quantum confinement41,46 and are therefore difficult to separate and be collected. Second, the interdomain charge-carrier transport is severely hindered by interfacial scattering effect. To further improve the performances of PDs, an innovative solution is urgently needed.

alide perovskites (HPs) have emerged as a superstar in optoelectronic and photovoltaic fields in recent years.1−8 They possess superior merits including high light absorption coefficient, large charge-carrier diffusion length, long chargecarrier lifetime, and excellent defects tolerance.9−13 Solar cells based on hybrid HPs have advanced power conversion efficiencies up to 22.1%.5 Photodetector (PD) is another kind of important optoelectronic device, which has been widely used in fields of environmental monitoring, biological sensing, imaging, and optical communication.14−17 Intensive investigations have been devoted to integrating HPs into versatile PDs prototypes.18−21 Early research mainly focused on polycrystalline film-sensitized PDs.22 The main problem of the film system is the large defect density at the grain boundaries,23−25 which play as trap centers and significantly recede the PDs performance. Soon afterward, bulk single crystals with extremely low defect density were utilized as photoresponse materials.26,27 However, the uncontrollability of their growth into bulk made them incompatible with PD fabrication techniques. Besides, these PDs usually exhibited narrow-band photoresponse.26,27 In pursuit of high-performance PDs based on polycrystalline film, large domain size, preferred orientations, and low intrinsic defect density were found to play major roles,28−31 which bring suppressed trapping and enhanced charge-carrier transport. Interestingly, while it is very difficult to improve the three parameters in polycrystalline system, films assembled with anisotropic HP microcrystallines, especially 2D homologous HPs, which have been extensively explored in optoelectronic and photovoltaic applications,32−36 seemingly better satisfy © 2017 American Chemical Society

Received: April 24, 2017 Accepted: May 23, 2017 Published: May 23, 2017 2565

DOI: 10.1021/acs.jpclett.7b00993 J. Phys. Chem. Lett. 2017, 8, 2565−2572

Letter

The Journal of Physical Chemistry Letters

Figure 1. As-prepared 2D free-standing microplatelets. (a) Schematic illustration of the 2D homologous HP structure. (b) XRD image and (c) absorption spectrum of as-prepared 2D microplatelets. (d) SEM image showing free-standing 2D microplatelets. (e) TEM image showing the single -crystal nature of the 2D microplatelets. The inset is the SAED pattern.

is difficult to identify due to weak quantum confinement effect. The few-layered HPs are undesirable in PDs due to overlarge exciton binding energy that hampers the separation and collection of photogenerated charge carriers.55 The scanning electron microscope (SEM) image in Figure 1d shows that the 2D microplatelets are free-standing with large edge size up to several micrometers. The large edge size is beneficial for longrange carrier transport providing increased mean-free path and reduced hopping, but the stacking of theses independent 2D microplatelets easily causes interfacial charge-carrier scattering. The transmission electron microscope (TEM) image in Figure 1e shows well-defined shape of the 2D microplatelets. High crystallinity can be confirmed by the highly ordered selected area electron diffraction (SAED) pattern in the inset. The treatment is schematic illustrated in Figure 2a. A cation exchange reaction was stimulated between OA+ in 2D microplatelets and FA+ in solution. Typically overlarge ammoniums such as OA+ cannot fit the cavity within the octahedra framework in HPs and therefore lead to 2D HPs,38,47,52,56 and if these overlarge ammoniums are substituted by suitable cations such as FA+, which correlates to a 3D HP crystallographic structure,57,58 then a dimensionality increase takes place, as shown in Figure 2b. Consequently, the electronic band structures change as well. The 2D HPs are self-organized quantum wells, as shown in Figure 2c,46,59 and the excitons are strongly confined, especially in the few-layered HPs, and are prone to undergo radiative recombination. However, after the treatment, the self-organized quantum-well electronic band structures are dismissed, followed by the reduction of exciton binding energy,46 and charge carriers are easier to separate and be collected. Detailed optical and structural characterizations before and after the treatment are given in Figure 3. The pristine film of 2D microplatelets was treated for various time, and the evolution of absorption spectra is presented in Figure 3a. Three features can be clearly observed: First, the characteristic absorption peaks of the few-layered 2D HPs gradually weakened and finally disappeared after 30 min of treatment. Second, the absorption onset experienced a red shift and finally located at ∼540 nm. Third, the light absorption was enhanced in the process, especially in the short-wavelength region. These

In this work, we report a novel postsynthetic treatment to simultaneously engineer the dimensionality and interface of 2D homologous HPs microcrystallines and significantly improve the performances of corresponding PDs. All of the procedures were carried out at room temperature in open environments. 2D (OA)2FAn−1PbnBr3n+1 (OA represents octadecylamine, FA is formamidine) microplatelets were drop-casted into pristine film. For treatment, the film was immersed in FA−acetate/ acetic acid solution, where cation exchange between OA+ in 2D HPs and FA+ in solution was stimulated. Two desirable improvements were consequently obtained: First, the dimensionality of the 2D HPs was increased, which reduces the quantum confinement effect and facilitates the separation of electrons and holes; second, the independent 2D microplatelets are fused, forming integrated channels and hence promoting the interdomain charge-carrier transport. As a result, the treated PDs show significantly improved performances compared with the pristine counterparts, the external quantum yield (EQE), and responsivity increased 3600 and 4200%, respectively, up to 7100% and 32 A/W, and the response time was shortened by more than two orders of magnitude to 0.25/1.45 ms. We believe this work provides important guidelines for future HPbased PD design. Figure 1a depicts the structure of 2D homologous HPs.41,45,47 They can be regarded as intermediates in the transition from 2D to 3D HPs; therefore, structural characteristics of both 2D and 3D HPs can be resolved in the X-ray diffraction (XRD) image, as shown in Figure 1b.41,48,49 A cubic phase of as-prepared 2D microplatelets can be inferred with preferential orientations of (001) and (002).50,51 The longchain ammonium capping the 2D microplatelets is OA+, which can be confirmed by the 2D characteristic peaks.52 The colloidal dispersion of as-prepared 2D microplatelets shows bright-green emission under a UV lamp (Figure S1). However, the absorption spectrum in Figure 1c unravels that as-prepared 2D microplatelets are not homogeneous in dimensionality, and few-layered HPs with various numbers of layers exist in the ensemble. The number of layers references that of 2D CsPbBr3 in a previous report considering FA+-induced red shift at the same time,53,54 and the absorption at ∼525 nm represents multilayered 2D microplatelets, of which the number of layers 2566


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the light scattering rather than real absorption.60 Consistent with the evolving trend of absorption spectra, the PL maxima also undergo a red shift upon prolonged treating time, and a gradual weakening of PL intensity accompanied (Figure 3b), which means a reduction of emissive loss after the treatment. In low-dimensional HPs, the large exciton binding energy increases the possibility of radiative recombination, and dimensionality increase by the treatment causes reduction of exciton binding energy and consequent convenience of separation of electrons and holes. Direct cognition of the treatment is provided in Figure S2, showing pristine and 30 min treated films under indoor daylight and their emissions under a UV lamp are shown in Figure S3. The change of XRD image after 30 min of treatment is shown in Figure 3c. The preferred orientation of pristine 2D microplatelets was inherited by the treated film showing uniaxial (001) and (002) planes. It is noteworthy that recently Kim et al. found films with uniaxial orientations own enhanced carrier mobility.29 Whereas such films usually require delicate optimizations of fabrication conditions,29,43 the strategy here is facile, which we believe will provide important methodological guidance for future research. The diffraction intensity significantly increased ∼15 times due to the dimensionality transition. The XRD of 2D homologous HPs comprises both in-plane and out-of-plane diffractions, leading to the coexistence of 2D characteristic peaks and 3D peaks, and the treatment here exchanges OA+ with FA+, which causes a decrease in out-of-plane diffraction and enhancement of inplane diffraction. Meanwhile, the 2D characteristic peaks totally disappeared. Moreover, the full width at half-maximun (fwhm) narrowed after the treatment (Figure 3d), which also supports the dimensionality increase caused by the in situ treatment.

Figure 2. Procedures of the treatment and consequent dimensionality increase. (a) Experimental procedures of the treatment. (b) Schematic illustration of the dimensionality increase and (c) consequent change of electronic band structures.

results agree with the dimensionality increase mentioned above and imply an enhanced light-harvesting capability. It is noteworthy that the long-wavelength absorption is caused by

Figure 3. Optical and structural change brought by the treatment. The evolution of (a) absorption spectra and (b) PL spectra of the films upon various treating time. (c) XRD images of pristine and 30 min treated films. (d) Comparison of the fwhm’s of the XRD images of pristine and 30 min treated films. 2567


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shows highly ordered spots, which reveals its single-crystalline essence. Therefore, we conclude that FA+ fuses adjacent microplatelets as a whole, forming integrated transporting channels for charge carriers (Figure 4b). An interesting phenomenon is that the 2D microplatelets are perpendicularly fused; this is because the fusion requires lattice match at the interfaces, and for cubic 2D microplatelets, 90° rotation exactly satisfies this requirement (Figure 4c). The intermicroplatelet fusion surely reduces the undesirable interfacial scattering effect and significantly enhances the carrier transport in the PDs, as schematically illustrated in Figure 4d,e To confirm that above effects of dimensionality increase and intermicroplatelet fusion are indeed caused by FA+ rather than by pure acetic acid, we treated the pristine film with pure acetic acid directly; all the other procedures were kept the same, and the treating time was set at 30 min. The color of the film barely changed, as shown in Figure S5, and the absorption spectrum of the film remained almost unchanged, showing multiple-peak feature (Figure S6). Consistently, the SEM image still shows free-standing 2D microplatelets (Figure S7). Therefore, we confirm that it is FA+ that plays a key role in the treatment. Both the dimensionality increase and intermicroplatelet fusion contribute to the improvement of charge-carrier transport. The conductivities of the treated films with various treating time were determined in the form of planar PDs, and the configuration of the PDs is shown in Figure S8. The result shows that the treatment indeed improves the conductivity of the film (Figure S9). Consequently, the performances of the treated PDs are remarkably improved compared with the pristine PDs. In the following the treated PDs represent PDs that were treated for 30 min. Figure 5a shows the I−V curves of pristine and treated PDs under 442 nm illumination of 3.2 mW/mm2. The voltage was swept stepwise from −3 to 3 V. The treated PDs show more than one order of magnitude higher photocurrent compared with the pristine counterparts, which means an enhanced photoelectric conversion capability.

Another improvement brought by the treatment is the intermicroplatelet fusion, which constructs integrated channels for charge-carrier transport and significantly meliorates the interfacial scattering effect. Figure S4 shows the time-dependent evolution of the microstructures of the film under prolonged treatment. Two features can be observed: first, the 2D morphology of the pristine microplatelets was well-preserved. Second, the previously independent microplatelets were gradually fused. SAED was then carried out at the joint marked with the red dashed circle (Figure 4a); the pattern in the inset

Figure 4. Intermicroplatelet fusion. (a,b) TEM images of the treated 2D microplatelets. The inset in panel a shows the single-crystal essence of the joint. (c) Lattice match of cubic 2D microplatelets in perpendicular directions. Schematic illustration of the carrier transport in (d) pristine and (e) treated PDs.

Figure 5. Enhanced performances in treated PDs. (a) Photocurrent, (b) I−t curves, (c) EQE, and (d) responsivity of the pristine and 30 min treated PDs. 2568


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Figure 6. Improvement of response speed in treated PDs. (a,b) I−t curves of the pristine PDs under various illumination frequencies. (c−f) I−t curves of the treated PDs under various illumination frequencies.

Figure 5b shows the I−t curves of both PDs under 442 nm illumination of 3.2 mW/mm2, and the photocurrent of the treated PDs is ∼20 times as large as that of the pristine PDs. Consistently, the EQE (Figure 5c) and responsivity (Figure 5d) of the treated PDs were also vastly improved; under 9 V bias the peak values reach 7100% and 32 A/W, respectively, which are approximately 36 and 42 times as high as those of the pristine PDs. The EQE and responsivity curves are consistent with the absorption curves, and a red- shift of the response onset can be observed in the treated PDs. The magnified EQE

and responsivity curves of the pristine PDs against wavelength are shown in Figures S10 and S11. The rise/decay time of the pristine and treated PDs was also measured as a reflection of charge-carrier mobility. The rise time is defined as time needed to rise from 10% peak value to 90% and inverse for decay time. Various illumination frequencies were executed to test their response speed. As shown in Figure 6a,b, the response of the pristine PDs was very slow, with the I−t curve became triangle-like when 10 Hz illumination was applied, which means the response of PDs could not follow the on/off frequency of illumination. The rise/ 2569



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decay time can be read from Figure 6a to be as long as 78/74 ms. However, for the treated PDs (Figure 6c−f), the current rose sharply when illuminated and rapidly dropped when sheltered. The I−t curve is still well-defined under a high frequency of 300 Hz, from which the rise/decay time is determined to be 0.25/1.45 ms. In conclusion, we have reported an innovative postsynthetic treatment to simultaneously engineer the dimensionality and interface of 2D homologous HPs and significantly improve the performances of corresponding PDs. 2D (OA)2FAn−1PbnBr3n+1 microplatelets film was immersed in FA+ solution, where exchange of OA+ with FA+ was stimulated and led to two improvements: First, a dimensionality increase was triggered to meliorate the quantum confinement effect and facilitate the separation of electrons and holes; second, the independent 2D microplatelets were fused, removing undesirable interfacial scattering. Therefore, the treated PDs showed significantly improved performances compared with the pristine counterparts, the EQE and responsivity increased 3600% and 4200% up to 7100% and 32 A/W, respectively, and the rise/decay time was shortened by two orders of magnitude to 0.25/1.45 ms. We believe this work provides important guidelines for future HPbased device construction from the viewpoint of intrinsic material properties.

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REFERENCES

(1) Kojima, A.; Teshima, K.; Shirai, Y.; Miyasaka, T. Organometal Halide Perovskites as Visible-Light Sensitizers for Photovoltaic Cells. J. Am. Chem. Soc. 2009, 131, 6050−6051. (2) Kim, H.-S.; Lee, C.-R.; Im, J.-H.; Lee, K.-B.; Moehl, T.; Marchioro, A.; Moon, S.-J.; Humphry-Baker, R.; Yum, J.-H.; Moser, J. E.; et al. Lead Iodide Perovskite Sensitized All-Solid-State Submicron Thin Film Mesoscopic Solar Cell with Efficiency Exceeding 9%. Sci. Rep. 2012, 2, 591. (3) Lee, M. M.; Teuscher, J.; Miyasaka, T.; Murakami, T. N.; Snaith, H. J. Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites. Science 2012, 338, 643−647. (4) Yang, W. S.; Noh, J. H.; Jeon, N. J.; Kim, Y. C.; Ryu, S.; Seo, J.; Seok, S. I. High-Performance Photovoltaic Perovskite Layers Fabricated through Intramolecular Exchange. Science 2015, 348, 1234−1237. (5) Jeon, N. J.; Noh, J. H.; Yang, W. S.; Kim, Y. C.; Ryu, S.; Seo, J.; Seok, S. I. Compositional Engineering of Perovskite Materials for High-Performance Solar Cells. Nature 2015, 517, 476−480. (6) Song, J.; Li, J.; Li, X.; Xu, L.; Dong, Y.; Zeng, H. Quantum Dot Light-Emitting Diodes Based on Inorganic Perovskite Cesium Lead Halides (CsPbX3). Adv. Mater. 2015, 27, 7162−7167. (7) Li, J.; Xu, L.; Wang, T.; Song, J.; Chen, J.; Xue, J.; Dong, Y.; Cai, B.; Shan, Q.; Han, B.; et al. 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. (8) Yantara, N.; Bhaumik, S.; Yan, F.; Sabba, D.; Dewi, H. A.; Mathews, N.; Boix, P. P.; Demir, H. V.; Mhaisalkar, S. Inorganic Halide Perovskites for Efficient Light-Emitting Diodes. J. Phys. Chem. Lett. 2015, 6, 4360−4364. (9) Xing, G.; Mathews, N.; Sun, S.; Lim, S. S.; Lam, Y. M.; Grätzel, M.; Mhaisalkar, S.; Sum, T. C. Long-Range Balanced Electron- and Hole-Transport Lengths in Organic-Inorganic CH3NH3PbI3. Science 2013, 342, 344−347. (10) Yin, W.-J.; Shi, T.; Yan, Y. Unique Properties of Halide Perovskites as Possible Origins of the Superior Solar Cell Performance. Adv. Mater. 2014, 26, 4653−4658. (11) Ponseca, C. S.; Savenije, T. J.; Abdellah, M.; Zheng, K.; Yartsev, A.; Pascher, T.; Harlang, T.; Chabera, P.; Pullerits, T.; Stepanov, A.; et al. Organometal Halide Perovskite Solar Cell Materials Rationalized: Ultrafast Charge Generation, High and Microsecond-Long Balanced Mobilities, and Slow Recombination. J. Am. Chem. Soc. 2014, 136, 5189−5192. (12) Dong, Q.; Fang, Y.; Shao, Y.; Mulligan, P.; Qiu, J.; Cao, L.; Huang, J. Electron-Hole Diffusion Lengths > 175 Mm in SolutionGrown CH3NH3PbI3 Single Crystals. Science 2015, 347, 967−970. (13) Walsh, A.; Scanlon, D. O.; Chen, S.; Gong, X. G.; Wei, S.-H. Self-Regulation Mechanism for Charged Point Defects in Hybrid Halide Perovskites. Angew. Chem. 2015, 127, 1811−1814. (14) Hu, X.; Zhang, X.; Liang, L.; Bao, J.; Li, S.; Yang, W.; Xie, Y. High-Performance Flexible Broadband Photodetector Based on Organolead Halide Perovskite. Adv. Funct. Mater. 2014, 24, 7373− 7380. (15) Sabri, Y. M.; Kandjani, A. E.; Ippolito, S. J.; Bhargava, S. K. Ordered Monolayer Gold Nano-Urchin Structures and Their Size Induced Control for High Gas Sensing Performance. Sci. Rep. 2016, 6, 24625. (16) Mueller, T.; Xia, F. N. A.; Avouris, P. Graphene Photodetectors for High-Speed Optical Communications. Nat. Photonics 2010, 4, 297−301. (17) Huo, N. J.; Yang, S. X.; Wei, Z. M.; Li, S. S.; Xia, J. B.; Li, J. B. Photoresponsive and Gas Sensing Field-Effect Transistors Based on Multilayer WS2 Nanoflakes. Sci. Rep. 2015, 4, 5209. (18) Dou, L.; Yang, Y.; You, J.; Hong, Z.; Chang, W.-H.; Li, G.; Yang, Y. Solution-Processed Hybrid Perovskite Photodetectors with High Detectivity. Nat. Commun. 2014, 5, 5404. (19) Dong, R.; Fang, Y.; Chae, J.; Dai, J.; Xiao, Z.; Dong, Q.; Yuan, Y.; Centrone, A.; Zeng, X. C.; Huang, J. High-Gain and Low-Driving-

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpclett.7b00993. As-prepared 2D microplatelet dispersion, pristine and treated films under indoor light, pristine and treated films under UV excitation, time-dependent SEM images of the treated films, pristine and acetic-acid-treated films, absorption spectrum of acetic-acid-treated film, SEM image of acetic-acid-treated film, schematic illustration of the PDs, time-dependent conductivity of the film, EQE of pristine PDs, and responsivity of the pristine PDs. (PDF)

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Letter

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Haibo Zeng: 0000-0002-0281-3617 Author Contributions †

D.Y., F.C., and Y.S. contributed equally to this work.

Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was financially supported by the National Key Basic Research Program of China (2014CB931702), NSFC (51572128, 21403109, 51502139), NSFC-RGC (5151101197), the National Key Research and Development Program of China (2016YFB0401701), the Fundamental Research Funds for the Central Universities (nos. 30915012205, 30916015106), Natural Science Foundation for Youths of Jiangsu Province of China (BK20140787), and PAPD of Jiangsu Higher Education Institutions and in USA by DoD (Grant W911NF-15-1-0650). 2570


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(39) Dou, L.; Wong, A. B.; Yu, Y.; Lai, M.; Kornienko, N.; Eaton, S. W.; Fu, A.; Bischak, C. G.; Ma, J.; Ding, T.; et al. Atomically Thin Two-Dimensional Organic-Inorganic Hybrid Perovskites. Science 2015, 349, 1518−1521. (40) Yuan, Z.; Shu, Y.; Tian, Y.; Xin, Y.; Ma, B. W. A Facile One-Pot Synthesis of Deep Blue Luminescent Lead Bromide Perovskite Microdisks. Chem. Commun. 2015, 51, 16385−16388. (41) Yuan, Z.; Shu, Y.; Xin, Y.; Ma, B. Highly Luminescent Nanoscale Quasi-2D Layered Lead Bromide Perovskites with Tunable Emissions. Chem. Commun. 2016, 52, 3887−3890. (42) Pathak, S.; Sakai, N.; Wisnivesky Rocca Rivarola, F.; Stranks, S. D.; Liu, J.; Eperon, G. E.; Ducati, C.; Wojciechowski, K.; Griffiths, J. T.; Haghighirad, A. A.; et al. Perovskite Crystals for Tunable White Light Emission. Chem. Mater. 2015, 27, 8066−8075. (43) Chen, A. Z.; Foley, B. J.; Ma, J. H.; Alpert, M. R.; Niezgoda, J. S.; Choi, J. J. Crystallographic Orientation Propagation in Metal Halide Perovskite Thin Films. J. Mater. Chem. A 2017, 5, 7796−7800. (44) Teunis, M. B.; Johnson, M. A.; Muhoberac, B. B.; Seifert, S.; Sardar, R. Programmable Colloidal Approach to Hierarchical Structures of Methylammonium Lead Bromide Perovskite Nanocrystals with Bright Photoluminescent Properties. Chem. Mater. 2017, 29, 3526−3537. (45) Quan, L. N.; Yuan, M.; Comin, R.; Voznyy, O.; Beauregard, E. M.; Hoogland, S.; Buin, A.; Kirmani, A. R.; Zhao, K.; Amassian, A.; et al. Ligand-Stabilized Reduced-Dimensionality Perovskites. J. Am. Chem. Soc. 2016, 138, 2649−2655. (46) Sichert, J. A.; Tong, Y.; Mutz, N.; Vollmer, M.; Fischer, S.; Milowska, K. Z.; García Cortadella, R.; Nickel, B.; Cardenas-Daw, C.; Stolarczyk, J. K.; et al. Quantum Size Effect in Organometal Halide Perovskite Nanoplatelets. Nano Lett. 2015, 15, 6521−6527. (47) Mitzi, D. B. Templating and Structural Engineering in OrganicInorganic Perovskites. J. Chem. Soc. Dalton 2001, 1−12. (48) Pathak, S.; Sakai, N.; Wisnivesky Rocca Rivarola, F.; Stranks, S. D.; Liu, J.; Eperon, G. E.; Ducati, C.; Wojciechowski, K.; Griffiths, J. T.; Haghighirad, A. A.; et al. Perovskite Crystals for Tunable White Light Emission. Chem. Mater. 2015, 27, 8066−8075. (49) Cao, D. H.; Stoumpos, C. C.; Farha, O. K.; Hupp, J. T.; Kanatzidis, M. G. 2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications. J. Am. Chem. Soc. 2015, 137, 7843−7850. (50) Saidaminov, M. I.; Abdelhady, A. L.; Maculan, G.; Bakr, O. M. Retrograde Solubility of Formamidinium and Methylammonium Lead Halide Perovskites Enabling Rapid Single Crystal Growth. Chem. Commun. 2015, 51, 17658−17661. (51) Dai, J.; Zheng, H.; Zhu, C.; Lu, J.; Xu, C. Comparative Investigation on Temperature-Dependent Photoluminescence of CH3NH3PbBR3 and CH(NH2)2PbBr3 Microstructures. J. Mater. Chem. C 2016, 4, 4408−4413. (52) Gonzalez-Carrero, S.; Espallargas, G. M.; Galian, R. E.; PerezPrieto, J. Blue-Luminescent Organic Lead Bromide Perovskites: Highly Dispersible and Photostable Materials. J. Mater. Chem. A 2015, 3, 14039−14045. (53) Bekenstein, Y.; Koscher, B. A.; Eaton, S. W.; Yang, P.; Alivisatos, A. P. Highly Luminescent Colloidal Nanoplates of Perovskite Cesium Lead Halide and Their Oriented Assemblies. J. Am. Chem. Soc. 2015, 137, 16008−16011. (54) Protesescu, L.; Yakunin, S.; Bodnarchuk, M. I.; Bertolotti, F.; Masciocchi, N.; Guagliardi, A.; Kovalenko, M. V. Monodisperse Formamidinium Lead Bromide Nanocrystals with Bright and Stable Green Photoluminescence. J. Am. Chem. Soc. 2016, 138, 14202− 14205. (55) Cohen, B.-E.; Wierzbowska, M.; Etgar, L. High Efficiency and High Open Circuit Voltage in Quasi 2D Perovskite Based Solar Cells. Adv. Funct. Mater. 2017, 27, 1604733. (56) Chen, J.; Gan, L.; Zhuge, F.; Li, H.; Song, J.; Zeng, H.; Zhai, T. A Ternary Solvent Method for Large-Sized Two-Dimensional Perovskites. Angew. Chem., Int. Ed. 2017, 56, 2390−2394. (57) Protesescu, L.; Yakunin, S.; Kumar, S.; Bär, J.; Bertolotti, F.; Masciocchi, N.; Guagliardi, A.; Grotevent, M.; Shorubalko, I.;

Voltage Photodetectors Based on Organolead Triiodide Perovskites. Adv. Mater. 2015, 27, 1912−1918. (20) Fang, Y.; Huang, J. Resolving Weak Light of Sub-Picowatt Per Square Centimeter by Hybrid Perovskite Photodetectors Enabled by Noise Reduction. Adv. Mater. 2015, 27, 2804−2810. (21) Shen, L.; Fang, Y.; Wang, D.; Bai, Y.; Deng, Y.; Wang, M.; Lu, Y.; Huang, J. A Self-Powered, Sub-Nanosecond-Response SolutionProcessed Hybrid Perovskite Photodetector for Time-Resolved Photoluminescence-Lifetime Detection. Adv. Mater. 2016, 28, 10794−10800. (22) Xia, H. R.; Li, J.; Sun, W. T.; Peng, L. M. Organohalide Lead Perovskite Based Photodetectors with Much Enhanced Performance. Chem. Commun. 2014, 50, 13695−13697. (23) Wang, L.; McCleese, C.; Kovalsky, A.; Zhao, Y.; Burda, C. Femtosecond Time-Resolved Transient Absorption Spectroscopy of CH3NH3PbI3 Perovskite Films: Evidence for Passivation Effect of PbI2. J. Am. Chem. Soc. 2014, 136, 12205−12208. (24) Tan, H.; Jain, A.; Voznyy, O.; Lan, X.; García de Arquer, F. P.; Fan, J. Z.; Quintero-Bermudez, R.; Yuan, M.; Zhang, B.; Zhao, Y.; et al. Efficient and Stable Solution-Processed Planar Perovskite Solar Cells Via Contact Passivation. Science 2017, 355, 722−726. (25) Xing, Y.; Sun, C.; Yip, H. L.; Bazan, G. C.; Huang, F.; Cao, Y. New Fullerene Design Enables Efficient Passivation of Surface Traps in High Performance P-I-N Heterojunction Perovskite Solar Cells. Nano Energy 2016, 26, 7−15. (26) Fang, Y.; Dong, Q.; Shao, Y.; Yuan, Y.; Huang, J. Highly Narrowband Perovskite Single-Crystal Photodetectors Enabled by Surface-Charge Recombination. Nat. Photonics 2015, 9, 679−686. (27) Dirin, D. N.; Cherniukh, I.; Yakunin, S.; Shynkarenko, Y.; Kovalenko, M. V. Solution-Grown CsPbBr3 Perovskite Single Crystals for Photon Detection. Chem. Mater. 2016, 28, 8470−8474. (28) Liu, Z.; Hu, J.; Jiao, H.; Li, L.; Zheng, G.; Chen, Y.; Huang, Y.; Zhang, Q.; Shen, C.; Chen, Q.; et al. Chemical Reduction of Intrinsic Defects in Thicker Heterojunction Planar Perovskite Solar Cells. Adv. Mater. 2017, 1606774. (29) Kim, D. H.; Park, J.; Li, Z.; Yang, M.; Park, J.-S.; Park, I. J.; Kim, J. Y.; Berry, J. J.; Rumbles, G.; Zhu, K. 300% Enhancement of Carrier Mobility in Uniaxial-Oriented Perovskite Films Formed by TopotacticOriented Attachment. Adv. Mater. 2017, 1606831. (30) Yin, J.; Cortecchia, D.; Krishna, A.; Chen, S.; Mathews, N.; Grimsdale, A. C.; Soci, C. Interfacial Charge Transfer Anisotropy in Polycrystalline Lead Iodide Perovskite Films. J. Phys. Chem. Lett. 2015, 6, 1396−1402. (31) Niu, G.; Yu, H.; Li, J.; Wang, D.; Wang, L. Controlled Orientation of Perovskite Films through Mixed Cations toward High Performance Perovskite Solar Cells. Nano Energy 2016, 27, 87−94. (32) Byun, J.; Cho, H.; Wolf, C.; Jang, M.; Sadhanala, A.; Friend, R. H.; Yang, H.; Lee, T.-W. Efficient Visible Quasi-2D Perovskite LightEmitting Diodes. Adv. Mater. 2016, 28, 7515−7520. (33) Kim, Y.-H.; Cho, H.; Lee, T.-W. Metal Halide Perovskite Light Emitters. Proc. Natl. Acad. Sci. U. S. A. 2016, 113, 11694−11702. (34) Cho, H.; Jeong, S.-H.; Park, M.-H.; Kim, Y.-H.; Wolf, C.; Lee, C.-L.; Heo, J. H.; Sadhanala, A.; Myoung, N.; Yoo, S.; et al. Overcoming the Electroluminescence Efficiency Limitations of Perovskite Light-Emitting Diodes. Science 2015, 350, 1222−1225. (35) Kim, H.; Lim, K.-G.; Lee, T.-W. Planar Heterojunction Organometal Halide Perovskite Solar Cells: Roles of Interfacial Layers. Energy Environ. Sci. 2016, 9, 12−30. (36) Lim, K.-G.; Ahn, S.; Kim, Y.-H.; Qi, Y.; Lee, T.-W. Universal Energy Level Tailoring of Self-Organized Hole Extraction Layers in Organic Solar Cells and Organic−Inorganic Hybrid Perovskite Solar Cells. Energy Environ. Sci. 2016, 9, 932−939. (37) Chen, S.; Shi, G. Two-Dimensional Materials for Halide Perovskite-Based Optoelectronic Devices. Adv. Mater. 2017, 1605448. (38) Tan, Z.; Wu, Y.; Hong, H.; Yin, J.; Zhang, J.; Lin, L.; Wang, M.; Sun, X.; Sun, L.; Huang, Y.; et al. Two-Dimensional (C4H9NH3)2PbBr4 Perovskite Crystals for High-Performance Photodetector. J. Am. Chem. Soc. 2016, 138, 16612−16615. 2571


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The Journal of Physical Chemistry Letters Bodnarchuk, M. I.; et al. Dismantling the “Red Wall” of Colloidal Perovskites: Highly Luminescent Formamidinium and Formamidinium−Cesium Lead Iodide Nanocrystals. ACS Nano 2017, 11, 3119− 3134. (58) 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. (59) Peng, B.; Li, J.; Li, Q.; Li, Y.; Zhu, H.; Zhang, L.; Wang, X.; Bi, L.; Lu, H.; Xie, J.; et al. Bose−Einstein Oscillators and the Excitation Mechanism of Free Excitons in 2D Layered Organic-Inorganic Perovskites. RSC Adv. 2017, 7, 18366−18373. (60) Lv, L. F.; Xu, Y. B.; Fang, H. H.; Luo, W. J.; Xu, F. J.; Liu, L. M.; Wang, B. W.; Zhang, X. F.; Yang, D.; Hu, W. D.; et al. Generalized Colloidal Synthesis of High-Quality, Two-Dimensional Cesium Lead Halide Perovskite Nanosheets and Their Applications in Photodetectors. Nanoscale 2016, 8, 13589−13596.

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