Ultrasensitive Perovskite Photodetectors by Co Partially Substituted

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Ultrasensitive perovskite photodetectors by Co partially substituted hybrid perovskite Luyao Zheng, Tao Zhu, Wenzhan Xu, Jie Zheng, Lei Liu, and Xiong Gong ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b02363 • Publication Date (Web): 02 Aug 2018 Downloaded from http://pubs.acs.org on August 2, 2018

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ACS Sustainable Chemistry & Engineering

Ultrasensitive perovskite photodetectors by Co partially substituted hybrid perovskite Luyao Zheng,1 Tao Zhu,1 Wenzhan Xu,1 Jie Zheng,2 Lei Liu*,1 and Xiong Gong*,1 1) College of Polymer Science and Polymer Engineering, The University of Akron, 250 South Forge Street, Akron, OH 44325, USA 2) Department of Chemical and Bimolecular Engineering, The University of Akron, Whitby Hall 211, Akron, OH 44325, USA Abstract In the past nine years, hybrid perovskite materials have attracted extensive research interests in both academic and industrial sectors. In this work, we report ultrasensitive solution-processed perovskite photodetectors by novel perovskite materials, where lead (Pb2+) is partially substituted by cobalt (Co2+). The CH3NH3Pb0.9Co0.1I3 thin film exhibits a cubic crystal structure, optimal thin film morphology, balanced charge carrier mobilities and suppressed defects compared to pristine CH3NH3PbI3 thin film with a tetragonal crystal structure, poor film morphology and unbalanced charge carrier mobilities. As a result, perovskite photodetectors fabricated by the CH3NH3Pb0.9Co0.1I3 thin film exhibit detectivities approximatively 1013 Jones (1 Jones=1 cm Hz1/2 W-1) in the spectra region from 350 nm to 800 nm at room temperature, and over 100 dB linear dynamic range. All these results indicate that our findings of partially substitution of Pb2+ by Co2+ can tune materials physical properties and further boost the device performance of perovskite photodetectors.

Keywords: hybrid perovskite, photodetection, Co2+ partially substituted perovskite, large grain size, detectivity.

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Introduction Sensitive detection of light through photodetectors (PDs) drains continuous attentions in the past years due to its various applications in both industrial and academic communities.1,2 In addition to device reengineering, the development of novel photovoltaic materials with superior physical properties, such as broadband spectral response, high absorption coefficient and excellent charge carrier mobility, as well as low-cost processablility is the footstone of PDs market.1-5 The past nine-years witnesses the exciting leap of device performance of perovskite photovoltaics which possess above advantages defeating its organic and inorganic conterparts.5-13 Not only power conversion efficiency (PCE) over 22% has been demonstrated from perovskite solar cells (PSCs), but also excellent detectivity, large linear dynamic range and ultrafast photoresponse have been reported from perovskite PDs (PPDs).5-13 However, all these works are generally on basis of pristine methylammonium lead triiodide (CH3NH3PbI3) perovskite which is consist of a ABX3 structure, where A is organic cation, B is core metal and X is halide anion.5-12 It was revealed that substitutions of A-site organic cation (CH3NH3+ or NH2CH=NH2+), B-site metal cation (Pb2+ or Sn2+) and X-site halide anion (Cl- or Br- or I-) in the hybrid perovskite crystal lattices would tune their physical properties dramatically, for example, crystal structure, optical bandgap and charge carrier mobility.13-26 Recently we found that by partially substitution of Pb2+ with Co2+, which shows a much smaller ionic radius (70 pm) than that (119 pm) of Pb2+, at B-site in the hybrid perovskite crystal lattices, the resultant novel hybrid perovskite thin films, CH3NH3Pb1-xCoxI3 (where x < 0.5 mol%), in particular, the CH3NH3Pb0.9Co0.1I3 thin film, exhibited cubic phase rather than tetragonal phase, significantly enlarged crystal grain size and balanced charge carrier mobilities, resulting in more than 20% PCE from PSCs.26


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In this study, we report room-temperature operated perovskite PDs (PPDs) by solutionprocessed CH3NH3Pb0.9Co0.1I3 thin film with spectral response from 350 nm to 800 nm. The cubic crystal structure, optimal thin film morphology, balanced charge carrier mobilities and suppressed defects of the CH3NH3Pb0.9Co0.1I3 thin film are favorable for boosting photocurrent and suppressing dark current. As a result, the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film exhibit detectivities approximatively of 1013 Jones (1 Jones = 1 cm Hz1/2 W-1), and linear dynamic range greater than 100 dB. All these results indicate that the partially substitution of Pb2+ by Co2+ could facilely modify the physical natures of hybrid perovskite materials and bring a remarkable enhancement to device performance of PPDs.

Experimental Section Materials: Lead iodide (PbI2, 99.999%), cobalt iodide (CoI2, 99.999%), hydroiodic acid (HCl, 37%) and methylamine (CH3NH2, 40 wt. % in H2O) were purchased from Sigma-Aldrich and used as received without further purification. Hydroiodic acid and methylamine were used to synthesis methylammonium iodide (CH3NH3I (MAI)) according to previous report.22 Poly(triaryl amine) (PTAA) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM, 99.5%) were purchased

from

Sigma-Aldrich

and

Solenne

BV,

respectively.

Anhydrous

N,

N-

dimethylformamide (DMF, 99.8%), anhydrous ethanol (>99.5%), anhydrous toluene (99.8%), anhydrous chlorobenzene (CB, 99.8%) were purchased from Sigma-Aldrich and used as received without further purification. Perovskite precursor preparation: PbI2 was dissolved into DMF solvent with a concentration of 400 mg mL-1, followed by stirring at 70 °C for about 12 hours (hrs) till the cloudy solution yields to transparent yellow solution. To make MAI:CoI2 solution with the concentration of MAI



maintained as 35 mg mL-1, MAI and CoI2 were firstly dissolved in ethanol solvent to obtain a concentration of 70 mg mL-1 and 88 mg mL-1 solutions, respectively. Then these two solutions were mixed together to form a solution according to the molar ratio of CoI2 to MAI as 0.1. Characterization of the CH3NH3Pb1-xCoxI3 (x=0 and 0.1) thin films: UV-vis absorption spectroscopy was investigated by the HP 8453 spectrophotometer. Top view scanning electron microscope (SEM) images were measured by using the JEOL-7401 ﬁeld emission scanning electron microscope. Thin film thicknesses were obtained by the Dektak 150 surface profilometer with a scan rate of 0.06 mm/s. X-ray photoelectron spectroscopies (XPS) were conducted on a PHI 5000 Versa Probe II scanning XPS microprobe to study the atomic components and real molar ratio of Co to Pb in the CH3NH3Pb0.9Co0.1I3 thin film. X-ray diffraction (XRD) patterns were measured to study the crystal structure based on Rigaku Ultima IV XRD System. Fabrication of perovskite photodetectors: The device structure is ITO/PTAA/CH3NH3Pb1xCoxI3/PC61BM/Al,

where ITO (indium tin oxide) substrate is pre-cleaned by ultrasonication with

detergent, acetone and isopropyl alcohol and dried overnight. UV-Ozone treatment of ITO substrate is conducted and the substrate is transferred in to a nitrogen filled glovebox before the deposition of a ~ 8 nm PTAA layer by spin coating from PTAA toluene solution (2 mg mL-1). After the thermal annealing (100 °C for 10 minutes (min)), ITO/PTAA substrates is maintained at 80 ºC. Then the warmed (70 ºC) PbI2 solution is spin casted at a spin-speed of 3000 RPM for 25 s with an acceleration time of 2 s, followed with thermal annealing at 70 ºC for 10 min on the hotplate, and then cooling down to room temperature. The ~ 380 nm CH3NH3Pb1-xCoxI3 thin films are formed by spin coating of either MAI or MAI:CoI2 solution on the top of PbI2 layer at a spin speed of 6000 RPM for 40 s with an acceleration time of 5 s, followed with thermal


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annealing at 100 ºC for 2 hrs on the hotplate. After cooling down to room-temperature, a ~ 60 nm PC61BM thin layer is spin-casted as electron extraction layer on the top of perovskite layer at a spin speed of 1800 RPM for 30 s with an acceleration time of 2 s from the PC61BM chlorobenzene solution (20 mg mL-1). Finally, a 100 nm thick aluminum (Al) electrode is thermally deposited through a shadow mask in the vacuum with the press of 1×10-6 mbar. The active device area is measured to be 0.045 cm2. Characterization of perovskite photodetectors: The current densities versus voltages (J-V) characteristics of PPDs are conducted in dark and under white light and a monochromatic light @ 500 nm from a Xenon lamp by a Keithley model 2400. The light intensity for white light is 100 mWcm-2, which is calibrated with a silicon reference cell, and the light intensity for the monochromatic light @ 500 nm is 0.28 mWcm-2, respectively. The external quantum efficiency (EQE) is obtained by using the quantum efficiency measurement system (QEX10) from PV measurements with a 300 W steady-state xenon lamp as the source light.

Results and Discussion The absorption spectra of the CH3NH3Pb1-xCoxI3 (where x= 0 and 0.1) thin film are presented in Figure 1. It is found that the optical absorption edge is red shifted from 780 nm for pristine CH3NH3PbI3 thin film to 790 nm for the CH3NH3Pb0.9Co0.1I3 thin film. This ~ 10 nm red shift probably comes from the decreased d-spacing of the crystal lattice.26 Moreover, a slightly enhanced absorbance is observed from the CH3NH3Pb0.9Co0.1I3 thin film in comparison with that of pristine CH3NH3PbI3 thin film, which implies that more photocurrent would be generated in the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film.



The atomic percentage of Co is calculated by the integrating peak areas of Co and Pb from XPS data with PHI MultiPak software (Figure S1 in Supporting Information (SI) 1). It is found that Co takes up 0.98% of the sum of Co and Pb elements in the CH3NH3Pb0.9Co0.1I3 thin film, for example. Thus, the final perovskite thin film is defined as CH3NH3Pb0.9Co0.1I3.26 Moreover, the CH3NH3Pb0.9Co0.1I3 thin film possesses a cubic structure and pristine CH3NH3PbI3 thin film possesses a tetragonal structure, based on the aspect of unit cell (SI 2). A cubic crystal structure could lead to a better and closer crystal stacking during the crystal growth due to the lower rotational energy barrier of CH3NH3+ compared to a tetragonal structure.27,28 Figure 2 displays SEM images of either CH3NH3PbI3 thin film or the CH3NH3Pb0.9Co0.1I3 thin film. The crystal domain of pristine CH3NH3PbI3 thin film is ~ 100 nm; whereas the crystal domain of the CH3NH3Pb0.9Co0.1I3 thin film is ~ 1 μm. Such large crystal domain is believed to provide higher charge carrier mobility and prolonged diffusion length, which would result in enhanced photocurrent.29-31 Moreover, pristine CH3NH3PbI3 thin film possesses large amount of pin-holes and defects, resulting in a pronounced leakage current and charge recombination, consequently high dark current and low photocurrent.29-31 Relative superior thin film morphology of CH3NH3Pb0.9Co0.1I3 indicates that the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film would exhibit enhanced photocurrent and suppressed dark current.29-31 In addition, it is found that the CH3NH3Pb0.9Co0.1I3 thin film and the CH3NH3Pb0.8Co0.2I3 thin film exhibit dramatically difference in film morphology (SI 3) even if both possess the same cubic crystal structure. As compared with the CH3NH3Pb0.9Co0.1I3 thin film, the CH3NH3Pb0.8Co0.2I3 thin film exhibits isolated crystal domains, larger crystal size and enlarged gaps between the large crystal domains. All these would cause severe leakage current, resulting in high dark current for the PDDs by the CH3NH3Pb0.8Co0.2I3 thin film. To further verify it, the J-


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V characterizations of the PPDs by the CH3NH3Pb1-xCoxI3 (x=0.1 and 0.2) thin films measured in dark are performed (SI 4). As expected, the PPDs by the CH3NH3Pb1-xCoxI3 (x=0.1) thin film exhibits suppressed dark current density. Moreover, the statistic population of pinhole areas of the CH3NH3Pb0.9Co0.1I3 and the CH3NH3Pb0.8Co0.2I3 thin films (SI 3) show that the integrated pinhole area in the CH3NH3Pb0.8Co0.2I3 thin film is larger than that in the CH3NH3Pb0.9Co0.1I3 thin film indicating that the CH3NH3Pb0.8Co0.2I3 thin film possesses poor film morphology. All these results demonstrate that the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film exhibiting better device performance compared to that of the CH3NH3Pb0.8Co0.2I3 thin film. Thus, our study is focused on the CH3NH3Pb0.9Co0.1I3 thin film rather than the CH3NH3Pb0.8Co0.2I3 thin film. It is found that the hole mobility is increased about four times while the electron mobility is decreased about one order of magnitude in the CH3NH3Pb0.9Co0.1I3 thin film compared with those in pristine CH3NH3PbI3 thin film (SI5). The more balanced hole and electron mobility was achieved in CH3NH3Pb0.9Co0.1I3 thin film with the lower limit mobility improved from 7.2×10-4 cm2/Vs of hole in CH3NH3PbI3 to 1.8×10-3 cm2/Vs of electron in CH3NH3Pb0.9Co0.1I3. Meanwhile, the hole and electron trap densities were both reduced in CH3NH3Pb0.9Co0.1I3 thin film probably due to the optimal film morphology. The device structure of PPDs is shown in Scheme 1, in which the ITO serves as the anode, PTAA is used as the hole extraction layer, PC61BM is used as the electron extraction layer, and Al serves as cathode, respectively. Noted that in the device structure under thin investigation, there is no interfacial engineering, such as the hole/electron blocking layers for promoting device performance of PPDs.12,16 Figure 3a shows the J-V characterizations of the PPDs by pristine CH3NH3PbI3 thin film and the CH3NH3Pb0.9Co0.1I3 thin film. As expected, the PPDs by the



CH3NH3Pb0.9Co0.1I3 thin film exhibit enhanced photocurrent and suppressed dark current in comparison with that by pristine CH3NH3PbI3 thin film. The responsivity (R), described as:3 R = ‫ܬ‬௣௛ /‫ܮ‬௟௜௚௛௧

(1)

where ‫ܬ‬௣௛ is the photocurrent density and ‫ܮ‬௟௜௚௛௧ is the light intensity, can be calculated. Biased at 0.1 V and at λ=500 nm, R is 1.1 A/W for the PDDs by pristine CH3NH3PbI3 thin film and 1.8 A/W for the PDDs by the CH3NH3Pb0.9Co0.1I3 thin film, respectively. The detectivity (D*) is estimated according to the equation:3 భ

‫ܴ = ∗ܦ‬/(2‫ܬݍ‬ௗ )మ

(2)

where ‫ܬ‬ௗ is the dark current density and q is elementary electric charge. The projected detectivity (D*) are estimated to be 6.1×1012 Jones for the PPDs by pristine CH3NH3PbI3 thin film, and 2.1×1013 Jones for the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film. Over 1013 Jones observed from the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film is the highest parameter among the PPDs with a similar device structure reported so far.12-21,32,33 Figure 3b presents the external quantum efficiency (EQE) spectra of the PPDs by pristine CH3NH3PbI3 thin film and the CH3NH3Pb0.9Co0.1I3 thin film. Both PPDs exhibit spectral response from 350 nm to 800 nm. But the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film exhibits considerable increased EQE values exceeding 90% versus that by pristine CH3NH3PbI3 thin film, demonstrating that effective charge transfer process takes place in the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film.34 Such high EQE values further confirm the potential of sensitive PPDs by the CH3NH3Pb0.9Co0.1I3 thin film, which is capable of efficient conversion from light to electrical signal. As shown in Figure 2, the CH3NH3Pb0.9Co0.1I3 thin film, which is significantly different to Sn2+ substituted perovskite materials,20,21 possess dramatically improved thin film morphology 8 ACS Paragon Plus Environment

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regarding to that by pristine CH3NH3PbI3 thin film. It was reported that PDs by optimal thin film morphology (less pinholes, larger crystal domains) exhibited low dark current and high photocurrent density,35,36 resulting in high detetectivity.13 Thus PPDs by the CH3NH3Pb0.9Co0.1I3 thin film exhibit enhanced detectivity and EQE values. Based on the EQE data extracted from Figure 3b, the R and ‫ ∗ܦ‬versus wavelength are calculated. As the results shown in Figure 4a-b, it clearly presents that an improvement over 2 times of R and ‫ ∗ܦ‬are observed from whole spectral region for the PPDs by the CH3NH3Pb0.9Co0.1I3 thin film in comparison with those by pristine CH3NH3PbI3 thin film. Figure 4c presents the photocurrent densities versus the incident light intensities of the PPDs fabricated by the CH3NH3Pb0.9Co0.1I3 thin film. The linear dynamic range (LDR) is another useful device performance parameter to evaluate device performance of PDs. The LDR is described as: ∗ LDR = 20 log(‫ܬ‬௣௛ /‫ܬ‬ௗ )

(3)

∗ where ‫ܬ‬௣௛ is the photocurrent measured at the light intensity of 1 mW/cm2.3 The PPDs fabricated

by the CH3NH3Pb0.9Co0.1I3 thin film processes a LDR of ~ 100 dB at room temperature, which is two times higher than that by pristine CH3NH3PbI3 thin film (~ 47 dB). It is worth to mention that this result obtained by efficient and low-cost processed CH3NH3Pb0.9Co0.1I3 PDs is comparable to that of commercial silicon-based PDs (120 dB)3 and undergoing narrow-band polymer PDs (~ 100 dB)3,5 but obviously defeats that (66 dB at 4.2 K) from InGaAs PDs,3 which all are capable of detecting light in near infrared region. The response times of PPDs are estimated by using an optical chopper with a controlled 532 nm laser pulse at a frequency of 2 kHz and the results are presented in Figure 4d. The rising and falling times of the PPDs based on pristine CH3NH3PbI3 thin film are 1.9 µs and 23.6 µs,



respectively. These response times are governed by the charge carrier mobility of pristine CH3NH3PbI3 thin film and de-trapping process, respectively. A comparable rising time (1.8 µs) and a slightly shortened falling time (19.7 µs) are achieved from the PPDs based on the CH3NH3Pb0.9Co0.1I3 thin film. The slightly shortened falling time is deemed to be arisen by the suppressed defects in the CH3NH3Pb0.9Co0.1I3 thin film.

Conclusions In this work, we reported ultrasensitive solution-processed perovskite photodetectors by novel hybrid perovskite materials, CH3NH3Pb0.9Co0.1I3, where Pb2+ is partially substituted by Co2+. Attribute to the dramatically smaller ionic radius of Co2+ than that of Pb2+, a small amount of doping of Co2+ promotes the formation of larger crystal grains and optimal morphology of the CH3NH3Pb0.9Co0.1I3 thin film in comparison with that of pristine CH3NH3PbI3 thin film, leading to suppressed leakage current and boosted photocurrent for perovskite photodetectors. Consequently, perovskite photodetectors fabricated by the CH3NH3Pb0.9Co0.1I3 thin film exhibits detectivity of ~ 1013 Jones as compared to that ~ 1012 Jones from the PDDs fabricated by pristine CH3NH3PbI3 thin film, operated under low bias (-0.1 V) at room temperature. Our studies opens a door to facilely promote device performance of perovskite photodetectors through partially substitution of Pb2+ at A cite crystal lattices.

Acknowledgements The authors acknowledge Air Force Office of Scientific Research (AFOSR) for the support of this work through the Organic Materials Chemistry Program (Grant Number: FA9550-15-1-0292, Program Manager: Dr. Kenneth Caster) for financial supports.


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Associated information Supporting information is available in the online version of the paper. Author information *Corresponding authors, Emails: [email protected] (XG); [email protected] (LL), Fax: (330)9723406



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References 1) Jha, A. R. Infrared technology, Wiley New York, 2000. 2) Rogalski, A. Competitive technologies of third generation infrared photon detectors, Rep. Prog. Phys. 2005, 68, 2267-2336. DOI 10.1088/0034-4885/68/10/R01. 3) Gong, X.; Tong, M.; Xia, Y.; Cai, W.; Moon, J. S.; Cao, Y.; Yu, G.; Shieh, C. L.; Nilsson, B.; Heeger, A. J. High-detectivity polymer photodetectors with spectral response from 300 nm to 1450 nm. Science. 2009, 325, 1665-1667. DOI 10.1126/science.1176706. 4) Konstantatos, G.; Sargent, E. H. Nanostructured materials for photon detection. Nat. Nanotechnol. 2010, 5, 391-400. DOI 10.1038/nnano.2010.78. 5) Zheng, L. Y.; Zhu, T.; Xu, W. Z.; Liu, L.; Zheng, J.; Gong, X.; Wudl, F. Solution-processed broadband polymer photodetectors with a spectral response of up to 2.5 µm by a low bandgap donor-acceptor conjugated copolymer. J. Mater. Chem. C. 2018, 6, 3634-3641. DOI 10.1039/C8TC00437D. 6) Grätzel, M. The rise of highly efficient and stable perovskite solar cells. Acc. Chem. Res. 2017, 50, 487-491. DOI 10.1021/acs.accounts.6b00492. 7) Correa-Baena, J. P.; Abate, A.; Saliba, M.; Tress, W.; Jacobsson, T. J.; Grätzel, M.; Hagfeldt, A. The rapid evolution of highly efficient perovskite solar cells. Energy Environ. Sci. 2017, 10, 710-727. DOI 10.1039/C6EE03397K. 8) Hodes,

G.

Perovskite-based

solar

cells.

Science.

2013,

342,

317-318.

DOI

10.1126/science.1245473. 9) Wang, K., Liu, C., Du, P., Zheng, J.; Gong, X. Bulk heterojunction perovskite hybrid solar cells

with

large fill

factor. Energy Environ. Sci.

10.1039/C5EE00222B.


2015,

8, 1245-1255. DOI

Page 13 of 22 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


10) Tan, H.; Jain, A.; Voznyy, O.; Lan, X.; de Arquer, F.P.G.; Fan, J.Z., Quintero-Bermudez, R., Yuan, M., Zhang, B., Zhao, Y.; Fan, F. Efficient and stable solution-processed planar perovskite solar cells via contact passivation. Science. 2017, 355, 722-726. DOI 10.1126/science.aai9081. 11) Bi, D., Yi, C., Luo, J., Décoppet, J.D., Zhang, F., Zakeeruddin, S.M., Li, X., Hagfeldt, A.; Grätzel, M. Polymer-templated nucleation and crystal growth of perovskite films for solar cells

with

efficiency greater than

21%.

Nat. Energy.

2016, 1, 16142. DOI

10.1038/nenergy.2016.142. 12) Yang, W. S.; Park, B.-W.; Jung, E. H.; Jeon, N. J.; Kim, Y. C.; Lee, D. U.; Shin, S. S.; Seo, J.; Kim, E. K.; Noh, J. H. Iodide management in formamidinium-lead-halide–based perovskite layers

for

efficient

solar

cells.

Science.

2017,

356,

1376-1379.

DOI

10.1126/science.aan2301. 13) Dou, L., Yang, Y.M., You, J., Hong, Z., Chang, W.H., Li, G. and Yang, Y. Solutionprocessed hybrid perovskite photodetectors with high detectivity. Nat. Commun. 2014, 5, 5404. DOI 10.1038/ncomms6404. 14) Liu, C.; Wang, K.; Yi, C.; Shi, X.; Du, P.; Smith, A. W.; Karim, A.; Gong, X. Ultrasensitive solution-processed perovskite hybrid photodetectors. J. Mater. Chem. C. 2015, 3, 66006606. DOI 10.1039/C5TC00673B. 15) Liu, C.; Wang, K.; Du, P.; Wang, E.; Gong, X.; Heeger, A. J. Ultrasensitive solutionprocessed broad-band photodetectors using CH3NH3PbI3 perovskite hybrids and PbS quantum

dots

as

light

harvesters.

Nanoscale.

10.1039/C5NR04575D.


2015,

7,

16460-16469.

DOI


16) Liu, C.; Peng, H.; Wang, K.; Wei, C.; Wang, Z.; Gong, X. PbS quantum dots-induced trapassisted charge injection in perovskite photodetectors. Nano Energy. 2016, 30, 27-35. DOI 10.1016/j.nanoen.2016.09.035. 17) Xu, W.; Guo, Y.; Zhang, X.; Zheng, L.; Zhu, T.; Zhao, D.; Hu, W.; Gong, X. Roomtemperature-operated ultrasensitive broadband photodetectors by perovskite incorporated with conjugated polymer and single-wall carbon nanotubes. Adv. Funct. Mater. 2018, 28, 1705541. DOI 10.1002/adfm.201705541. 18) 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. DOI 10.1002/adfm.201402020. 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‐voltage photodetectors based on organolead triiodide perovskites. Adv. Mater. 2015, 27, 1912-1918. DOI 10.1002/adma.201405116. 20) Hao, F., Stoumpos, C. C., Chang, R. P.; Kanatzidis, M. G. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells. J. Am. Chem. Soc. 2014, 136, 8094-8099. DOI 10.1021/ja5033259. 21) Ogomi, Y., Morita, A., Tsukamoto, S., Saitho, T., Fujikawa, N., Shen, Q., Toyoda, T., Yoshino, K., Pandey, S.S., Ma, T.; Hayase, S. CH3NH3SnxPb(1–x)I3 Perovskite solar cells covering up to 1060 nm. J. Phys. Chem. Lett. 2014, 5, 1004-1011. DOI 10.1021/jz5002117. 22) Wang, Z.K., Li, M., Yang, Y.G., Hu, Y., Ma, H., Gao, X.Y.; Liao, L.S. High efficiency Pb– In binary metal perovskite solar cells. Adv. Mater. 2016, 28, 6695-6703. DOI 10.1002/adma.201600626.


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23) Eperon, G. E., Beck, C. E.; Snaith, H. J. Cation exchange for thin film lead iodide perovskite interconversion. Mater. Horizons. 2016, 3, 63-71. DOI 10.1039/C5MH00170F. 24) Yan, W., Rao, H., Wei, C., Liu, Z., Bian, Z., Xin, H.; Huang, W. Highly efficient and stable inverted planar solar cells from (FAI)x(MABr)1− xPbI2 perovskites. Nano Energy. 2017, 35, 62-70. DOI 10.1016/j.nanoen.2017.03.001. 25) Zhao, Y.; Zhu, K. Organic–inorganic hybrid lead halide perovskites for optoelectronic and electronic

applications.

Chem.

Soc.

Rev.

2016,

45,

655-689.

DOI

10.1039/C4CS00458B. 26) Xu, W., Zheng, L., Zhang, X., Cao, Y., Meng, T., Wu, D., Liu, L., Hu, W.; Gong, X. Efficient perovskite solar cells fabricated by Co partially substituted hybrid perovskite. Adv. Energy Mater. 2018, 8, 1703178. DOI 10.1002/aenm.201703178. 27) Brivio, F., Walker, A.B.; Walsh, A. Structural and electronic properties of hybrid perovskites for high-efficiency thin-film photovoltaics from first-principles. Apl. Mater. 2013, 1, 042111. DOI 10.1063/1.4824147. 28) Brivio, F., Frost, J.M., Skelton, J.M., Jackson, A.J., Weber, O.J., Weller, M.T., Goni, A.R., Leguy, A.M., Barnes, P.R.; Walsh, A. Lattice dynamics and vibrational spectra of the orthorhombic, tetragonal, and cubic phases of methylammonium lead iodide. Phys. Rev. B. 2015, 92, 144308. DOI 10.1103/PhysRevB.92.144308. 29) Nie, W., Tsai, H., Asadpour, R., Blancon, J.C., Neukirch, A.J., Gupta, G., Crochet, J.J., Chhowalla, M., Tretiak, S., Alam, M.A.; Wang, H.L. High-efficiency solution-processed perovskite solar cells with millimeter-scale grains. Science. 2015, 347, 522-525. DOI 10.1126/science.aaa0472.



Page 16 of 22

30) Liu, C., Wang, K., Yi, C., Shi, X., Smith, A.W., Gong, X.; Heeger, A.J. Efficient perovskite hybrid photovoltaics via alcohol‐vapor annealing treatment. Adv. Funct. Mater. 2016, 26, 101-110. DOI 10.1002/adfm.201504041. 31) Wang, K., Liu, C., Du, P., Zhang, H.L.; Gong, X. Efficient perovskite hybrid solar cells through a homogeneous high-quality organolead iodide layer. Small. 2015, 11, 3369-3376. DOI 10.1002/smll.201403399. 32) Sutherland, B. R., Johnston, A. K., Ip, A. H., Xu, J., Adinolfi, V., Kanjanaboos, P.; Sargent, E. H. Sensitive, fast, and stable perovskite photodetectors exploiting interface engineering. ACS Photonics. 2015, 2, 1117-1123. DOI 10.1021/acsphotonics.5b00164. 33) Zhu, H. L., Cheng, J., Zhang, D., Liang, C., Reckmeier, C. J., Huang, H., Rogach, A. L.; Choy, W. C. Room-temperature solution-processed NiOx: PbI2 nanocomposite structures for realizing high-performance perovskite photodetectors. ACS Nano. 2016, 10, 6808-6815. DOI 10.1021/acsnano.6b02425. 34) Stamplecoskie, K. G., Manser, J. S.; Kamat, P. V. Dual nature of the excited state in organic– inorganic lead halide perovskites. Energy Environ. Sci.

2015, 8, 208-215. DOI

10.1039/C4EE02988G. 35) Bi, C., Wang, Q., Shao, Y., Yuan, Y., Xiao, Z.; Huang, J. Non-wetting surface-driven highaspect-ratio crystalline grain growth for efficient hybrid perovskite solar cells. Nat. Comm. 2015, 6, 7747. DOI 10.1038/ncomms8747. 36) Sharenko, A.; Toney, M.F. Relationships between lead halide perovskite thin-film fabrication, morphology, and performance in solar cells. J. Am. Chem. Soc. 2015, 138, 463-470. DOI 10.1021/jacs.5b10723.


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Scheme 1. Device structure of perovskite photodetectors.



Figure 1. Absorption spectra of the CH3NH3Pb1-xCoxI3 (where x= 0 and 0.1) thin films.


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Figure 2. SEM images of (a) pristine CH3NH3PbI3 thin film, and (b) the CH3NH3Pb0.9Co0.1I3 thin film.



Figure 3. (a) The J-V characterizations of the PPDs by the CH3NH3Pb1-xCoxI3 (x=0 and 0.1) thin films measured in dark and under illumination, and (b) the EQE spectra of the PPDs by the CH3NH3Pb1-xCoxI3 (x=0 and 0.1) thin films.


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Figure 4. (a) The responsivity and (b) detectivity of the PDDs fabricated by the CH3NH3Pb1-xCoxI3 thin films (where x = 0 and 0.1), (c) the linear dynamic range of the PDDs fabricated by the CH3NH3Pb1-xCoxI3 thin films (where x = 0 and 0.1), and (d) the transient photocurrent of the PPDs fabricated by the CH3NH3Pb1-xCoxI3 thin films (where x = 0 and 0.1).



For Table of Contents Use Only

Ultrasensitive solution-processed perovskite photodetectors by novel CH3NH3Pb1-xCoxI3 thin films, where lead cation (Pb2+) is partially substituted by cobalt cation (Co2+) for tuning its physical properties.


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Ultrasensitive Perovskite Photodetectors by Co Partially Substituted

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