Process-, Solvent- and Chemical Engineering for Solution Processed Organic-Inorganic Lead Halide Perovskite Solar Cells

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This thesis explores the preparation of thin films of organic-inorganic lead halide perovskites (ABX3) through solution processing methods for integration into solar cell devices. A low temperature single-step crystallization method, known as the instantaneous perovskite crystallization process (IPC), was developed for depositing CH3NH3PbX3 (X = halide) thin films. The study examines the effects of short-chain lead (II) carboxylate precursors, processing parameters, and chemical modifications on the X-site of hybrid perovskite thin films with methylammonium cation, utilizing various spectroscopic and analytical techniques. Efficient planar organic-inorganic lead halide perovskite solar cells were achieved in both n-i-p and p-i-n device stacks, with a maximum power conversion efficiency of 15.6% at 75 °C for CH3NH3PbI3 thin films using Pb(CH3COO)2 and CH3NH3I precursors in N,N-dimethylformamide. Additionally, protic ionic liquids containing methylammonium cation and carboxylate anion were synthesized and used as alternative solvents for processing hybrid lead halide perovskites. A ternary solvent system, including methylammonium propionate, acetonitrile, and dimethyl sulfoxide, enabled the preparation of (MA0.15FA0.85)Pb(I0.85Br0.15)3 thin films via sequential deposition. The study also investigated the surface modification of mesoporous TiO2 thin films with alkali bis-(trifluoromethanesulfonyl) imide (TFSI), revealing a trade-