Growth of single-crystalline MAPbI3 perovskite film by a modified space-confined inverse temperature crystallization method

Single crystalline (SC) metal halide perovskite absorber film can outperform its polycrystalline counterpart in power conversion efficiency and stability due to the absence of grain boundaries. However, SC perovskite film's direct growth on charge selective contact layer coated substrates for solar cell applications is not widely explored. In this study, SC methylammonium lead iodide (MAPbI3) perovskite film is directly grown on charge selective (electron and hole transport) contact layer coated substrates (TiO2 coated fluorine doped tin oxide (FTO) glass substrate and poly(triarylamine) (PTAA) coated indium tin oxide (ITO) glass substrate) by inverse temperature crystallization (ITC) method. The PTAA/ITO substrate's hydrophobic nature led to faster ion migration and controlled nucleation, resulting in large-sized SC MAPbI3 perovskite film. X-ray diffraction of the MAPbI3/PTAA/ITO showed SC nature with diffraction from (200) and (400) planes, indicating that the film is majorly (100) oriented. The MAPbI3 film grown on TiO2/FTO is found to be relatively small in size (< 1 mm), majorly oriented in the (110) plane with diffraction also from other planes indicating polycrystalline nature. Long-term stability studies over 1500 h show that SC MAPbI3 films show more endurance to ambient conditions than polycrystalline MAPbI3. The growth time of 50 h was reduced to 30 h by employing antisolvent-assisted ITC, resulting in ultra-stable circular shaped films suitable for photovoltaic applications.