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Planar perovskite solar cells with metal oxide transport layers by co-evaporation and hybrid vapor-solution sequential method

Soltanpoor, Wiri
The recent success in achieving beyond 25% efficiency with perovskite solar cells (PSC) has called for further upgrading the fabrication techniques to meet the scalability requirements of the photovoltaic (PV) industry. Co-evaporation and a hybrid vapor-solution technique have been shown to produce uniform and efficient planar PSCs. Therefore, in this study, co-evaporation method was optimized studying the partial pressure of the organic precursor. Later electron transport layers in n-i-p and p-i-n structures were addressed achieving 13.0% and 16.1% efficiencies, respectively. Besides, mixed-halide perovskites were fabricated following a hybrid sequential method focusing on the deposition rate of PbI2 and a solution of methylammonium-halides to control the crystallization and morphology of the perovskite layer. This conferred efficiencies up to 19.8% in the case of MAPbI3-X-YBrXClY with 90 hours of operational stability. This is an important measure towards scalability due to the uniform deposition of the first inorganic layer by vacuum-deposition. As another step towards the scalability of perovskite PV, radio frequency (RF) magnetron sputtering was devised to deposit NiOX as a hole transport layer with wide bandgap, matched band structure with perovskite, and stability. The effect of Ar-partial pressure, deposition rate on the optoelectronic properties of the sputtered NiOX was investigated. The passivation of NiOX using organic (Poly-TPD) and inorganic (CuO) materials boosted the overall efficiency of the PSCs by 2.2% and 1.2%, respectively. Finally, Cu doping NiOX via co-sputtering enhanced the efficiency of the PSCs by 3%. This thesis provides a benchmark for applying scalable methods (from evaporation to sputtering) towards efficient PSCs.