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Tuning the electron beam evaporation parameters for the production of hole and electron transport layers for perovskite solar cells

Coşar, Mustafa Bura
This study evaluates the use of electron beam evaporation technique for the deposition of electron and hole transport layers for perovskite solar cells where cell productions were performed in n-i-p structure. NiO and TiO layers were studied for hole transport layer and TiO2 and Nb2O5 layers were deposited for electron transport purposes. To optimize the suitable evaporation parameters for efficient perovskite cell production, single layers of each material were deposited at different conditions of oxygen flow rate, deposition temperature, deposition rate and plasma assistance. The structural, optical, and electrical properties of each layer were associated with the produced perovskite cells. Oxygen addition provides better cell performances in the case of both NiO and TiO hole transport layers; however, oxygen requirement of the TiO thin films were optimized at a lower value than NiO layers. When hole transport layer thicknesses were obtained at 75 nm and 50 nm for NiO and TiO, conversion efficiencies for these cells were recorded as best performances of 6.13 % and 5.72 %. Nb2O5 compact electron transport layers were used in the production of the perovskite solar cells at planar, heat treated planar and Nb2O5- mesoporous TiO2 bilayer architectures. Although, oxygen addition is crucial for the plasma assisted condition, it is detrimental for the unassisted condition for all types of architectures. It is detected that plasma assistance yields better performance compared to unassisted deposition. The use of Nb2O5-mesoporous TiO2 bilayer provides sharp enhancement in the cell performance and 13.87 % conversion efficiency was sustained.