3,4-Phenylenedioxythiophene (PheDOT) Based Hole-Transporting Materials for Perovskite Solar Cells

Chen, Jian,Chen, Bai-Xue,Zhang, Fang-Shuai,Yu, Hui-Juan,Ma, Shuang,Kuang, Dai-Bin,Shao, Guang,Su, Cheng-Yong

, p. 1043 - 1049 (2016)

Two new electron-rich molecules based on 3,4-phenylenedioxythiophene (PheDOT) were synthesized and successfully adopted as hole-transporting materials (HTMs) in perovskite solar cells (PSCs). X-ray diffraction, absorption spectra, photoluminescence spectra, electrochemical properties, thermal stabilities, hole mobilities, conductivities, and photovoltaic parameters of PSCs based on these two HTMs were compared with each other. By introducing methoxy substituents into the main skeleton, the energy levels of PheDOT-core HTM were tuned to match with the perovskite, and its hole mobility was also improved (1.33×10-4 cm2 V-1 s-1, being higher than that of spiro-OMeTAD, 2.34×10-5 cm2 V-1 s-1). The PSC based on MeO-PheDOT as HTM exhibits a short-circuit current density (Jsc) of 18.31 mA cm-2, an open-circuit potential (Voc) of 0.914 V, and a fill factor (FF) of 0.636, yielding an encouraging power conversion efficiency (PCE) of 10.64 % under AM 1.5G illumination. These results give some insight into how the molecular structures of HTMs affect their performances and pave the way for developing high-efficiency and low-cost HTMs for PSCs.

Surface Photovoltage Spectroscopy Study of Ultrasonically Sprayed-Aerosol CH3NH3PbI3 Perovskite Crystals

Henjongchom, Nakorn,Rujisamphan, Nopporn,Tang, I-Ming,Supasai, Thidarat

, (2018)

A simple deposition process for preparing crystalline semiconductors with low degrees of disorder is of paramount interest for both device applications and research investigations. This study centers on the ultrasonically sprayed-aerosol based approach for preparing crystals of methylammonium lead trihalide perovskite (CH3NH3PbI3). The surface photovoltage (SPV) spectra are found to depend strongly on the preparation conditions, with the SPV signals (below the material's band gap) providing information on the defect states. The measured values of tail states near the band gap (Et) are found to be about 21 and 52 meV for the CH3NH3PbI3 crystals prepared by the ultrasonically sprayed-on and spun casting approaches, respectively.

Control of Perovskite Crystal Growth by Methylammonium Lead Chloride Templating

Binek, Andreas,Grill, Irene,Huber, Niklas,Peters, Kristina,Hufnagel, Alexander G.,Handloser, Matthias,Docampo, Pablo,Hartschuh, Achim,Bein, Thomas

, p. 1199 - 1204 (2016)

State-of-the-art solar cells based on methylammonium lead iodide (MAPbI3) now reach efficiencies over 20 %. This fast improvement was possible with intensive research in perovskite processing. In particular, chloride-based precursors are known to have a positive influence on the crystallization of the perovskite. Here, we used a combination of in-situ X-ray diffraction and charge-transport measurements to understand the influence of chloride during perovskite crystallization in planar heterojunction solar cells. We show that MAPbCl3 crystallizes directly after the deposition of the starting solution and acts as a template for the formation of MAPbI3. Additionally, we show that the charge-carrier mobility doubles by extending the time for the template formation. Our results give a deeper understanding of the influence of chloride in the synthesis of MAPbI3 and illustrate the importance of carefully controlling crystallization for reproducible, high-efficiency solar cells.

Exploration of organic-inorganic hybrid perovskites for surface-enhanced infrared spectroscopy of small molecules

Chen, Jia,Mo, Zhi-Hong,Yang, Xiao,Zhou, Hai-Ling,Gao, Qin

, p. 6949 - 6952 (2017)

The organic-inorganic hybrid perovskites efficiently enhance the infrared absorption of small molecules. It is suggested that the quantum wells of perovskites enable the electrons of the perovskites to be excited by light in the infrared region. The exploration has opened a new path for chemical sensing through infrared spectroscopy.

Nanostructured TiO2/CH3NH3PbI3 heterojunction solar cells employing spiro-OMeTAD/Co-complex as hole-transporting material

Noh, Jun Hong,Jeon, Nam Joong,Choi, Yong Chan,Nazeeruddin, Md. K.,Graetzel, Michael,Seok, Sang Il

, p. 11842 - 11847 (2013)

For using 2,2′,7,7′-tetrakis(N,N′-di-p- methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as a hole conductor in solar cells, it is necessary to improve its charge-transport properties through electrochemical doping. With the aim of fabricating efficient mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cells, we used tris[2-(1H-pyrazol-1-yl)-4-tert- butylpyridine)cobalt(iii) tris(bis(trifluoromethylsulfonyl) imide)] (FK209) as a p-dopant for spiro-OMeTAD. The mixture of spiro-OMeTAD, FK209, lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI), and 4-tert-butylpyridine (TBP) exhibited significantly higher performance than mixtures of pristine spiro-OMeTAD, spiro-OMeTAD, and FK209, and spiro-OMeTAD, Li-TFSI, and TBP. Such a synergistic effect between the Co-complex and Li-TFSI in conjunction with spiro-OMeTAD effectively improved the power conversion efficiency (PCE) of the fabricated solar cells. As a result, we achieved PCE of 10.4%, measured under standard solar conditions (AM 1.5G, 100 mW cm-2).

Atmospheric pressure chemical vapor deposition of methylammonium bismuth iodide thin films

Chen, Xiao,Myung, Yoon,Thind, Arashdeep,Gao, Zhengning,Yin, Bo,Shen, Meikun,Cho, Sung Beom,Cheng, Peifu,Sadtler, Bryce,Mishra, Rohan,Banerjee, Parag

, p. 24728 - 24739 (2017)

We demonstrate the atmospheric pressure chemical vapor deposition of methyl ammonium bismuth iodide ((CH3NH3)3Bi2I9 or MA3Bi2I9) films. MA3Bi2I9 possesses an indirect optical bandgap of 1.80 eV and a room temperature excitonic peak at 511 nm. In contrast to recent reports, the films are n-type semiconductors with a room temperature carrier concentration of 3.36 × 1018 cm-3 and a Hall mobility of 18 cm2 V-1 s-1, which are superior to those of solution-processed, undoped films. The precursors used for the deposition are methylammonium iodide and bismuth iodide which are co-sublimated at 199 °C and 230 °C, respectively, in an Ar flow inside a tube furnace with a variable temperature profile. The substrate temperature is set at 160 °C, and dense polycrystalline films (～775 nm thick) are deposited. Extensive characterization combined with first-principles density functional theory calculations unravels the synthesis-structure-property relationship in these films. The degradation of properties under ambient conditions results from film oxidation with a characteristic bi-exponential decay in resistivity, signifying a fast surface oxidation followed by a slower oxidation of the bulk.

Photocurrent induced by conducting channels of hole transporting layer to adjacent photoactive perovskite sensitized TiO2 thin film: Solar cell paradigm

Ameen, Sadia,Akhtar, M. Shaheer,Seo, Hyung-Kee,Shin, Hyung-Shik

, p. 12786 - 12794 (2014)

A high performance perovskite solar cell was fabricated using the distinguished morphology of polyaniline nanoparticles (PANI-NPs) as an efficient hole transporting layer (HTL) with methylammonium lead iodide perovskite (CH3NH3PbI3) as sensitizer. PANI-NPs were simply synthesized by the oxidative chemical polymerization of aniline monomer at 0-5 °C. A reasonable solar-to-electricity conversion efficiency of ～6.29% with a high short circuit current (JSC) of ～17.97 mA/cm2 and open circuit voltage (VOC) of ～0.877 V were accomplished by Ag/PANI-NPs/CH3NH3PbI3/mp-anatase-TiO2/bl-TiO2/FTO perovskite solar cell. The transient photocurrent and photovoltage studies revealed that the fabricated solar cell showed better charge transport time, diffusion coefficient, diffusion length, and charge collection efficiency. Herein, the use of PANI-NPs as the HTL improved the charge carrier generation and the charge collection efficiency of the fabricated solar cell.

Observation of internal photoinduced electron and hole separation in hybrid two-dimentional perovskite films

Liu, Junxue,Leng, Jing,Wu, Kaifeng,Zhang, Jun,Jin, Shengye

, p. 1432 - 1435 (2017)

Two-dimensional (2D) organolead halide perovskites are promising for various optoelectronic applications. Here we report a unique spontaneous charge (electron/hole) separation property in multilayered (BA)2(MA)n-1PbnI3n+1 (BA = CH3(CH2)3NH3+, MA = CH3NH3+) 2D perovskite films by studying the charge carrier dynamics using ultrafast transient absorption and photoluminescence spectroscopy. Surprisingly, the 2D perovskite films, although nominally prepared as n = 4 , are found to be mixture of multiple perovskite phases, with n = 2, 3, 4 and ≈ ∞, that naturally align in the order of n along the direction perpendicular to the substrate. Driven by the band alignment between 2D perovskites phases, we observe consecutive photoinduced electron transfer from small-n to large-n phases and hole transfer in the opposite direction on hundreds of picoseconds inside the 2D film of ～358 nm thickness. This internal charge transfer efficiently separates electrons and holes to the upper and bottom surfaces of the films, which is a unique property beneficial for applications in photovoltaics and other optoelectronics devices.

Naphtho[1,2-: B:4,3- b ′]dithiophene-based hole transporting materials for high-performance perovskite solar cells: Molecular engineering and opto-electronic properties

Cui, Bin-Bin,Yang, Ning,Shi, Congbo,Yang, Shuangshuang,Shao, Jiang-Yang,Han, Ying,Zhang, Liuzhu,Zhang, Qingshan,Zhong, Yu-Wu,Chen, Qi

, p. 10057 - 10063 (2018)

As a pump for extracting carriers from the absorber to the cathode, hole transporting materials (HTMs) play indispensable roles in promoting the power conversion efficiencies (PCE) of perovskite solar cells (PSCs). In this context, we present two simple HTMs using 2,2′-(1,2-phenylene) bisthiophene or naphtho[1,2-b:4,3-b′]dithiophene as a π-bridge to link two electron-donor units (4′,4′′-dimethoxytriphenylamine): PBT and NDT. Their frontier molecular orbital energies match well with those of perovskites as is consistent with the DFT calculation results. The PCE measured under mimetic solar illumination (AM 1.5, 100 mW cm-2) increases from 13.6% (PBT) to 18.8% (NDT), which surpass that of the spiro-OMeTAD (18.1%) reference. The modified annulated core in NDT makes it perform better in photovoltaic conversion than PBT. The reason for this is discussed from aspects of hole mobility, charge collection probability (Pc) and recombination kinetics.

Thermal and Structural Characterization of Methylammonium- and Formamidinium-Halide Salts

Harding, Alexander J.,Dobson, Kevin D.,Ogunnaike, Babatunde A.,Shafarman, William N.

, (2021)

Four organic halide salts of interest to alloyed perovskite solar cell fabrication are characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), powder X-ray diffraction (XRD), and thermogravimetric analysis. The chemical and crystal structures of methylammonium iodide (MAI), methylammonium bromide (MABr), and formamidinium iodide (FAI) are confirmed, and the experimental ATR-FTIR spectrum and XRD pattern of formamidinium bromide (FABr) are presented. The enthalpy, ΔH vap, and entropy, ΔS vap, of vaporization are quantified for each salt and are used to estimate their vapor pressures in the temperature range of 150–300 °C. MAI, MABr, and FAI have similar vapor pressures in this temperature range, whereas FABr has a higher vapor pressure in the temperature range of 150–240 °C. These data provide a foundation for achieving effective control of vapor phase concentrations for vapor processing of alloyed perovskite solar cells.

In situ investigation of degradation at organometal halide perovskite surfaces by X-ray photoelectron spectroscopy at realistic water vapour pressure

Chun-Ren Ke, Jack,Walton, Alex S.,Lewis, David J.,Tedstone, Aleksander,O'Brien, Paul,Thomas, Andrew G.,Flavell, Wendy R.

, p. 5231 - 5234 (2017)

Near-ambient-pressure X-ray photoelectron spectroscopy enables the study of the reaction of in situ-prepared methylammonium lead iodide (MAPI) perovskite at realistic water vapour pressures for the first time. We show that MAPI decomposes directly to PbI

Highly stable hole-conductor-free CH3NH3Pb(I1-xBrx)3 perovskite solar cells with carbon counter electrode

Zong, Beibei,Fu, Wuyou,Liu, Huijing,Huang, Liwen,Bala, Hari,Wang, Xiaodong,Sun, Guang,Cao, Jianliang,Zhang, Zhanying

, p. 1006 - 1012 (2018)

In this work, high stable perovskite solar cells (PSCs) based carbon counter electrode were fabricated in the air environment with 30% of humidity, in which the perovskite CH3NH3Pb(I1-xBrx)3 were used

Inkjet printing and instant chemical transformation of a CH3NH3PbI3/nanocarbon electrode and interface for planar perovskite solar cells

Wei, Zhanhua,Chen, Haining,Yan, Keyou,Yang, Shihe

, p. 13239 - 13243 (2014)

A planar perovskite solar cell that incorporates a nanocarbon hole-extraction layer is demonstrated for the first time by an inkjet printing technique with a precisely controlled pattern and interface. By designing the carbon plus CH3NH3I ink to transform PbI2 in situ to CH3NH3PbI3, an interpenetrating seamless interface between the CH3NH3PbI3 active layer and the carbon hole-extraction electrode was instantly constructed, with a markedly reduced charge recombination compared to that with the carbon ink alone. As a result, a considerably higher power conversion efficiency up to 11.60% was delivered by the corresponding solar cell. This method provides a major step towards the fabrication of low-cost, large-scale, metal-electrode-free but still highly efficient perovskite solar cells.

Well-Defined Thiolated Nanographene as Hole-Transporting Material for Efficient and Stable Perovskite Solar Cells

Cao, Jing,Liu, Yu-Min,Jing, Xiaojing,Yin, Jun,Li, Jing,Xu, Bin,Tan, Yuan-Zhi,Zheng, Nanfeng

, p. 10914 - 10917 (2015)

Perovskite solar cells (PSCs) have been demonstrated as one of the most promising candidates for solar energy harvesting. Here, for the first time, a functionalized nanographene (perthiolated trisulfur-annulated hexa-peri-hexabenzocoronene, TSHBC) is employed as the hole transporting material (HTM) in PSCs to achieve efficient charge extraction from perovskite, yielding the best efficiency of 12.8% in pristine form. The efficiency is readily improved up to 14.0% by doping with graphene sheets into TSHBC to enhance the charge transfer. By the HOMO-LUMO level engineering of TSHBC homologues, we demonstrate that the HOMO levels are critical for the performance of PSCs. Moreover, beneficial from the hydrophobic nature of TSHBC, the devices show the improved stability under AM 1.5 illumination in the humidity about 45% without encapsulation. These findings open the opportunities for efficient HTMs based on the functionalized nanographenes utilizing the strong interactions of their functional groups with perovskite.

Effects of annealing temperature on stability of methylammonium lead iodide perovskite powders

Padchasri, Jintara,Yimnirun, Rattikorn

, p. 63 - 69 (2017)

The methylammonium lead iodide (CH3NH3PbI3 or MAPbI) material is currently investigated as active material in perovskite solar cells. Its stability, high optical band gap, low processing temperature and abundant elemental constituents provide numerous advantages over most powder absorber materials. In this work, the stability of MAPbI perovskite powders under different annealing temperature conditions was examined. X-ray diffraction (XRD) measurement demonstrated that the direct mixing synthesis method was able to produce a highly crystalline MAPbI material in a tetragonal phase structure. Thermal stability measurement based on the Simultaneous Thermal Analyzer (STA) indicated that the MAPbI was stable below 275 °C. The optical properties were characterized by employing refraction spectroscopy, which confirmed a direct bandgap of 1.53 eV in MAPbI perovskite powders. FT-Raman and XPS spectra confirmed the existence of organic groups. The annealing affected significantly the phase formation and stability of MAPbI. A small amount of lead iodide (PbI2), a product of the degradation, was observed with increasing annealing temperature. Therefore, a suitable annealing temperature should be chosen to produce MAPbI powders, which in turn will result in a high performance perovskite solar cell.

Hydrogen Bonding Controls the Structural Evolution in Perovskite-Related Hybrid Platinum(IV) Iodides

Evans, Hayden A.,Fabini, Douglas H.,Andrews, Jessica L.,Koerner, Mitchell,Preefer, Molleigh B.,Wu, Guang,Wudl, Fred,Cheetham, Anthony K.,Seshadri, Ram

, p. 10375 - 10382 (2018)

We describe the solid-state structural evolution in four hybrid hexaiodoplatinate(IV) compounds, demonstrating the increasingly important role that extended hydrogen bonding plays in directing the structure across the series. The compounds are A2PtI6, where A is one of the following amines: ammonium, NH4+ methylammonium, CH3NH3+ formamidinium, CH(NH2)2+ guanidinium, C(NH2)3+. These are closely related in structure and properties to the hybrid halide perovskites of lead(II) that have recently established their prowess in optoelectronics. The first three of these compounds crystallize in the vacancy-ordered double perovskite A2PtI6 ( indicates a vacant site) structure in the K2PtCl6 archetype, despite the relatively large perovskite tolerance factors involved. The last compound, (GUA)2PtI6, crystallizes in a vacancy-ordered variant of the hexagonal CsNiCl3 structure: the K2MnF6 structure. A combination of solid-state 195Pt and 1H NMR spectroscopy and detailed density functional theory calculations helps to reveal structural trends and establish the hydrogen-bonding tendencies. The calculations and measured optical properties support the surprising observation in these iodosalt compounds that, for smaller A cations, the conduction bands are considerably disperse, despite lacking extended I-Pt-I connectivity.

Facile synthesis of organic–inorganic hybrid perovskite CH3NH3PbI3 microcrystals

Jia, Xianyu,Hu, Ziyang,Zhu, Yubing,Weng, Tianyao,Wang, Jie,Zhang, Jing,Zhu, Yuejin

, p. 270 - 274 (2017)

The organic–inorganic hybrid perovskite CH3NH3PbI3 is becoming an interesting material in the field of optoelectronic application. Most of the previous research focused on thin film and crystal growth of this material. Here we describe the rapid preparation of perovskite CH3NH3PbI3 microcrystals using a facile synthesis method at room temperature. By using ultrasound assisted solutions of PbI2 and CH3NH3I precursors in acid solvents, a single-phase perovskite was obtained. X-ray diffraction data reveal that the prepared CH3NH3PbI3 crystals possess a tetragonal structure. FE-SEM and TEM images show the morphology and grain size of CH3NH3PbI3 crystals. UV-VIS-NIR and PL measurements indicate that the perovskite crystals show a slight reduced bandgap, accompanying with red shift, compared with the perovskite polycrystalline films. DSC-TGA demonstrates that the perovskite microcrystals show the better thermal stability than that of the perovskite films, which suggests the wide potential application.

Visualizing Carrier Diffusion in Individual Single-Crystal Organolead Halide Perovskite Nanowires and Nanoplates

Tian, Wenming,Zhao, Chunyi,Leng, Jing,Cui, Rongrong,Jin, Shengye

, p. 12458 - 12461 (2015)

Single-crystal CH3NH3PbX3 (X = I-, Cl-, Br-) perovskite nanowires (NWs) and nanoplates (NPs), which demonstrate ultracompact sizes and exceptional photophysical properties, offer promises f

CH3NH3PbI3 perovskite/fullerene planar-heterojunction hybrid solar cells

Jeng, Jun-Yuan,Chiang, Yi-Fang,Lee, Mu-Huan,Peng, Shin-Rung,Guo, Tzung-Fang,Chen, Peter,Wen, Ten-Chin

, p. 3727 - 3732 (2013)

All-solid-state donor/acceptor planar-heterojunction (PHJ) hybrid solar cells are constructed and their excellent performance measured. The deposition of a thin C60 fullerene or fullerene-derivative (acceptor) layer in vacuum on a CH3NH3PbI3 perovskite (donor) layer creates a hybrid PHJ that displays the photovoltaic effect. Such heterojunctions are shown to be suitable for the development of newly structured, hybrid, efficient solar cells. Copyright

Efficient planar-heterojunction perovskite solar cells achieved via interfacial modification of a sol-gel ZnO electron collection layer

Kim, Junghwan,Kim, Geunjin,Kim, Tae Kyun,Kwon, Sooncheol,Back, Hyungcheol,Lee, Jinho,Lee, Seoung Ho,Kang, Hongkyu,Lee, Kwanghee

, p. 17291 - 17296 (2014)

The importance of interfacial engineering as a new strategy for improving the power conversion efficiencies (PCEs) of planar-heterojunction (PHJ) perovskite solar cells is highlighted in this study. With our optimized interfacial modification, we demonstrated efficient PHJ perovskite solar cells with a high PCE of 12.2% using a sol-gel-processed ZnO ECL modified by [6,6]-phenyl C61 butyric acid methyl ester (PCBM). This journal is

High-performance perovskite memristor based on methyl ammonium lead halides

Yan, Kai,Peng, Ming,Yu, Xiao,Cai, Xin,Chen, Si,Hu, Hsienwei,Chen, Buxin,Gao, Xue,Dong, Bin,Zou, Dechun

, p. 1375 - 1381 (2016)

Memristors are devices that can store and process information based on their switchable internal resistance. Although these devices offer better performance than the conventional technology, the use of materials such as complex metal oxides usually requires high-temperature annealing processing or vacuum processing such as sputtering, which complicates the fabrication of the devices and hinders their development for practical use. Here we show a high-performance memristor based on organometal trihalides and electrochemical active metals, which achieved an on-off current ratio of 1.9 × 109. The devices can be solution-processed at low temperature and in air, which may be further developed into printable electronics. We explored the influence of different metal electrodes and device structures on memristor performance and the results indicated the great potential of methyl ammonium lead halide perovskite for information storage and computing. Our work provides new application prospects for these materials and may also contribute to the better understanding of other perovskite-based optoelectronic devices.

Potential replacement to lead: Alkali metal potassium and transition metal zinc in organo-metal halide perovskite materials

Rani, Mamta,Saini, G. S. S.,Singh, Baljinder,Soleimanioun, Nazilla,Tripathi, S. K.

, (2021)

Following the plenty of research work on solving the issue of the popular and promising perovskite solar cells, this article is focused on methylammonium lead iodide (MAPbI3) and the alternative element which can perform as efficiently as lead does. Here, not only the different concentrations of the substitute element are investigated, but also higher stable perovskite is introduced as well. Several characterization techniques are used to assure the validity of the results. The large alkali metal potassium (K) and the transition metal zinc (Zn) are studied side by side. The results are interesting when the 5% concentration of the KI alloyed MAPbI3 shows considerable transport properties like 54 nm diffusion length, 245 × 10?9 Sm?1 photoconductivity, and significant majority and minority carrier mobility–lifetime product as compared to MAPbI3 but it becomes more interesting when after 60 days the 5% concentration of the aged ZnCl2 alloyed MAPbI3 turns into a leading element of this research by showing high stability among of all. The morphology investigations show both perovskite materials achieve large islands which are desired morphology in perovskite materials as well.

Controlled Synthesis of Organic/Inorganic van der Waals Solid for Tunable Light-Matter Interactions

, p. 7800 - 7808 (2015)

High-quality organic and inorganic van der Waals (vdW) solids are realized using methylammonium lead halide (CH3NH3PbI3) as the organic part (organic perovskite) and 2D inorganic monolayers as counterparts. By stacking on

Electrospray technique in fabricating perovskite-based hybrid solar cells under ambient conditions

Lin, Pei-Ying,Chen, Yueh-Ying,Guo, Tzung-Fang,Fu, Yaw-Shyan,Lai, Li-Chung,Lee, Chung-Kwang

, p. 10985 - 10991 (2017)

In this work, we utilized the electrospray technique to deposit the solidified crystal precursors on the substrate to investigate the transition processes in forming an orthorhombic methylammonium lead iodide film for fabricating perovskite planar heterojunction solar cells. The formation of solidified crystal precursors by the electrospray technique improves the de-wetting of the perovskite film on the substrate. Judicious selection of the applied voltage in the electrospray process generates crystal precursors of the appropriate dimensions. These as-electrosprayed crystals are the solid-state reactants for the halogen exchange and they form a uniformly covered film on the substrate under suitable annealing conditions. The hybrid device prepared by the electrospray technique exhibits a power conversion efficiency of 9.3%, a short-circuit current of 19.71 mA cm?2, an open-circuit voltage of 0.87 V, and a fill factor of 0.55. The electrospray technique with the solid-state reaction mechanism proposed in this paper would be ideal for the large-area coating of a perovskite active layer, and thus has potential for use in real mass production.

The Role of Oxygen in the Degradation of Methylammonium Lead Trihalide Perovskite Photoactive Layers

Aristidou, Nicholas,Sanchez-Molina, Irene,Chotchuangchutchaval, Thana,Brown, Michael,Martinez, Luis,Rath, Thomas,Haque, Saif A.

, p. 8208 - 8212 (2015)

In this paper we report on the influence of light and oxygen on the stability of CH3NH3PbI3 perovskite-based photoactive layers. When exposed to both light and dry air the mp-Al2O3/CH3NH3PbI3 photoactive layers rapidly decompose yielding methylamine, PbI2, and I2 as products. We show that this degradation is initiated by the reaction of superoxide (O2-) with the methylammonium moiety of the perovskite absorber. Fluorescent molecular probe studies indicate that the O2- species is generated by the reaction of photoexcited electrons in the perovskite and molecular oxygen. We show that the yield of O2- generation is significantly reduced when the mp-Al2O3 film is replaced with an mp-TiO2 electron extraction and transport layer. The present findings suggest that replacing the methylammonium component in CH3NH3PbI3 to a species without acid protons could improve tolerance to oxygen and enhance stability.

1T-2H MoSe2 modified MAPbI3 for effective photocatalytic hydrogen evolution

Cai, Yifei,Chen, Jinxi,Lou, Yongbing,Zhang, Tiantian

supporting information, (2021/10/25)

Organic-inorganic perovskites such as iodine methylamine lead (MAPbI3) shows superb photocatalytic prospect in the field of solar energy driven photocatalysis. However, its catalytic performance is insufficient due to serious charge recombination. In this article, 1T-2H MoSe2/MAPbI3 composites were obtained by simple electrostatic adsorption method. The results of photocatalytic hydrogen production showed that 10 wt% 1T-2H MoSe2/MAPbI3 performed the best hydrogen evolution rate of 552.93 μmol·h?1·g?1, which was 23 times than that of pure MAPbI3 (23.13 μmol·h?1·g?1). The long-term cyclic stability test also indicated that 1T-2H MoSe2/MAPbI3 composites have good stability. The excellent hydrogen evolution rate activity is thoroughly investigated by optical/optoelectrochemical measurements, showing that 1T-2H MoSe2 as a co-catalyst can effectively transfer electrons and promote the separation of photogenerated charge. This study provided a reference for further exploration of MAPbI3-based catalysts with excellent catalytic activity.

Formation of cubic perovskite alloy containing the ammonium cation of 2D perovskite for high performance solar cells with improved stability

Jung, Mi-Hee

, p. 32590 - 32603 (2021/12/07)

The perovskite solar cells have demonstrated to be strong competitors for conventional silicon solar cells due to their remarkable power conversion efficiency. However, their structural instability is the biggest obstacle to commercialization. To address these issues, we prepared (CH3NH3)1-x(HC(NH2)2)xPbI3 (CH3NH3 = MA, HC(NH2)2 = FA) perovskite alloys that contain ethylammonium (EA, CH3CH2NH3+) and benzylammonium (BA, C6H5CH2NH3+) cations with no new additional two-dimensional (2D) perovskite phases. The crystal structures of alloy perovskites exhibit the cubic phase, which decreased the cation disorder and the intrinsic instability compared to 3D MAPbI3 perovskite. The band gaps of the alloy perovskites are almost the same as the corresponding 3D perovskites, which exhibit a high refractive index, a large absorption coefficient, and paramagnetic properties for the production of high performance photovoltaic devices. After we constructed the solar cell with the configuration of regular (n-i-p) solar cells using the alloy perovskites, the power conversion efficiencies (PCE) of the MA0.83EA0.17PbI3 perovskite solar cell showed the highest efficiency, which was 10.22%, under 1 sun illumination.