Abstract
Solar cell devices are one of the most promising technologies for generating green energy. Forefront perovskite-based solar cells have increased worldwide hope for solving global warming issues. Tight bandgap formamidinium lead iodide (TB-FAPbI(3)) perovskite as an active layer to absorb sunlight along with a desired electron transport layer (ETL) can produce efficient and stable perovskite solar cells (PSCs). Here, TB-FAPbI(3) with tin oxide (SnO2) as an ETL was employed to fabricate PSCs. These PSCs recorded a low champion efficiency of 18.35%. A cobalt-doped SnO2 layer was designed to increase the efficiency of TB-FAPbI(3) solar cells. The modified SnO2 boosted the solar cell efficiency to 20.10% due to the improved conductivity of the ETL and increased charge transfer phenomena in the PSCs. From one side, electron transfer is facilitated at the ETL/perovskite interface. On another side, the reduced surface defects on the fabricated perovskite layer over the modified ETL diminish charge traps in the solar cell. In addition, cobalt doping does not hinder the light transmission from the SnO2 into the perovskite layer. The modified SnO2 assists in the formation of a more compact TB-FAPbI(3) layer and promotes the stability properties of PSCs.