Investigation of Thermally Induced Degradation in CH3NH3PbI3 Perovskite Solar Cells using In-situ Synchrotron Radiation Analysis

In this study, we employ a combination of various in-situ surface analysis techniques to investigate the thermally induced degradation processes in MAPbI3 perovskite solar cells (PeSCs) as a function of temperature under air-free conditions (no moisture and oxygen). Through a comprehensive approach that combines in-situ grazing-incidence wide-angle X-ray diffraction (GIWAXD) and high-resolution X-ray photoelectron spectroscopy (HR-XPS) measurements, we confirm that the surface structure of MAPbI3 perovskite film changes to an intermediate phase and decomposes to CH3I, NH3, and PbI2 after both a short (20 min) exposure to heat stress at 100 °C and a long exposure (>1 hour) at 80 °C. Moreover, we observe clearly the changes in the orientation of CH3NH3+ organic cations with respect to the substrate in the intermediate phase, which might be linked directly to the thermal degradation processes in MAPbI3 perovskites. These results provide important progress towards improved understanding of the thermal degradation mechanisms in perovskite materials and will facilitate improvements in the design and fabrication of perovskite solar cells with better thermal stability.

[1]  M. Johnston,et al.  Formamidinium lead trihalide: a broadly tunable perovskite for efficient planar heterojunction solar cells , 2014 .

[2]  Nam-Gyu Park,et al.  Highly Reproducible Perovskite Solar Cells with Average Efficiency of 18.3% and Best Efficiency of 19.7% Fabricated via Lewis Base Adduct of Lead(II) Iodide. , 2015, Journal of the American Chemical Society.

[3]  Yixin Zhao,et al.  Organic-inorganic hybrid lead halide perovskites for optoelectronic and electronic applications. , 2016, Chemical Society reviews.

[4]  K. P. Ong,et al.  Structural Evolution in Methylammonium Lead Iodide CH3NH3PbI3. , 2015, The journal of physical chemistry. A.

[5]  Tsutomu Miyasaka,et al.  Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. , 2009, Journal of the American Chemical Society.

[6]  Eric T. Hoke,et al.  A layered hybrid perovskite solar-cell absorber with enhanced moisture stability. , 2014, Angewandte Chemie.

[7]  Sergei Tretiak,et al.  High-efficiency two-dimensional Ruddlesden–Popper perovskite solar cells , 2016, Nature.

[8]  T. Oku.  Crystal Structures of CH3NH3PbI3 and Related Perovskite Compounds Used for Solar Cells , 2015 .

[9]  T. Miyasaka,et al.  Atomistic origins of CH3NH3PbI3 degradation to PbI2 in vacuum , 2015 .

[10]  Wei Chen,et al.  Efficient and stable large-area perovskite solar cells with inorganic charge extraction layers , 2015, Science.

[11]  M. Grätzel.  The light and shade of perovskite solar cells. , 2014, Nature materials.

[12]  Saif A. Haque,et al.  Light and oxygen induced degradation limits the operational stability of methylammonium lead triiodide perovskite solar cells , 2016 .

[13]  H. Lee,et al.  Exploration of fabrication methods for planar CH3NH3PbI3 perovskite solar cells , 2016 .

[14]  Qi Chen,et al.  Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers. , 2016, Nature nanotechnology.

[15]  Alessandro Mattoni,et al.  Methylammonium fragmentation in amines as source of localized trap levels and the healing role of Cl in hybrid lead-iodide perovskites , 2015 .

[16]  Peng Gao,et al.  A molecularly engineered hole-transporting material for efficient perovskite solar cells , 2016, Nature Energy.

[17]  Guangda Niu,et al.  Review of recent progress in chemical stability of perovskite solar cells , 2015 .

[18]  Thomas Rath,et al.  The Role of Oxygen in the Degradation of Methylammonium Lead Trihalide Perovskite Photoactive Layers. , 2015, Angewandte Chemie.

[19]  Jenny Nelson,et al.  Reversible Hydration of CH3NH3PbI3 in Films, Single Crystals, and Solar Cells , 2015 .

[20]  J. Noh,et al.  Efficient inorganic–organic hybrid heterojunction solar cells containing perovskite compound and polymeric hole conductors , 2013, Nature Photonics.

[21]  Nam-Gyu Park,et al.  Organometal Perovskite Light Absorbers Toward a 20% Efficiency Low-Cost Solid-State Mesoscopic Solar Cell , 2013 .

[22]  T. Oku,et al.  Microstructures and photovoltaic properties of perovskite-type CH3NH3PbI3 compounds , 2014 .

[23]  J. Teuscher,et al.  Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites , 2012, Science.

[24]  Lijia Liu,et al.  Tracking the formation of methylammonium lead triiodide perovskite , 2015 .

[25]  H. Snaith,et al.  Structural and optical properties of methylammonium lead iodide across the tetragonal to cubic phase transition: implications for perovskite solar cells , 2016 .

[26]  Chun-Guey Wu,et al.  Planar heterojunction perovskite/PC71BM solar cells with enhanced open-circuit voltage via a (2/1)-step spin-coating process , 2014 .

[27]  Jay B. Patel,et al.  Bandgap‐Tunable Cesium Lead Halide Perovskites with High Thermal Stability for Efficient Solar Cells , 2016 .

[28]  N. Park,et al.  Lead Iodide Perovskite Sensitized All-Solid-State Submicron Thin Film Mesoscopic Solar Cell with Efficiency Exceeding 9% , 2012, Scientific Reports.

[29]  Steffen Meyer,et al.  Degradation observations of encapsulated planar CH3NH3PbI3 perovskite solar cells at high temperatures and humidity , 2015 .

[30]  H. Rensmo,et al.  Chemical and Electronic Structure Characterization of Lead Halide Perovskites and Stability Behavior under Different Exposures—A Photoelectron Spectroscopy Investigation , 2015 .

[31]  Lijia Liu,et al.  Dissociation of Methylammonium Cations in Hybrid Organic-Inorganic Perovskite Solar Cells. , 2016, Nano letters.

[32]  Lijia Liu,et al.  Self-Alignment of the Methylammonium Cations in Thin-Film Organometal Perovskites. , 2014, The journal of physical chemistry letters.

[33]  Y. Qi,et al.  Thermal degradation of CH3NH3PbI3 perovskite into NH3 and CH3I gases observed by coupled thermogravimetry–mass spectrometry analysis , 2016 .

[34]  Peng Gao,et al.  Effect of Annealing Temperature on Film Morphology of Organic–Inorganic Hybrid Pervoskite Solid‐State Solar Cells , 2014 .

[35]  Aslihan Babayigit,et al.  Intrinsic Thermal Instability of Methylammonium Lead Trihalide Perovskite , 2015 .

[36]  Jeffrey A. Christians,et al.  Transformation of the excited state and photovoltaic efficiency of CH3NH3PbI3 perovskite upon controlled exposure to humidified air. , 2015, Journal of the American Chemical Society.

[37]  Fuzhi Huang,et al.  Probing Molecular and Crystalline Orientation in Solution‐Processed Perovskite Solar Cells , 2015 .

[38]  Henry J. Snaith,et al.  Stability of Metal Halide Perovskite Solar Cells , 2015 .

[39]  Sang Il Seok,et al.  Solvent engineering for high-performance inorganic-organic hybrid perovskite solar cells. , 2014, Nature materials.

[40]  Sang Il Seok,et al.  High-performance photovoltaic perovskite layers fabricated through intramolecular exchange , 2015, Science.

[41]  Jinli Yang,et al.  Investigation of CH3NH3PbI3 degradation rates and mechanisms in controlled humidity environments using in situ techniques. , 2015, ACS nano.