Efficiency enhancement of Cs_0.1(CH₃NH₃)_0.9PbI₃ perovskite solar cell by surface passivation using iso-butyl ammonium iodide

Efficiency enhancement of Cs_0.1(CH₃NH₃)_0.9PbI₃ solar cell devices was performed by using iso-butyl ammonium iodide (IBA) passivated on Cs_0.1(CH₃NH₃)_0.9PbI₃ films. The n-i-p structure of perovskite solar cell devices was fabricated with the structure of FTO/SnO₂/Cs_0.1(CH₃NH₃)_0.9PbI₃ and IBA/Spiro-OMeTAD/Ag. The effect of different weights of IBA passivated on Cs-doped PSCs was systematically investigated and compared with non-passivated devices. It was found that the 5mg IBA-passivated devices exhibited a high PCE of 15.4% higher than 12.6% of non-IBA-passivated devices. The improvement of photovoltaic parameters of the 5 mg IBA-passivated devices can be clearly observed compared to the Cs-doped device. The better performance of the IBA-passivated device can be confirmed by the reduction of PbI₂  phase in the crystal structure, lower charge recombination rate, lower charge transfer resistance, and improved contact angle of perovskite films. Therefore, IBA passivation on Cs_0.1(CH₃NH₃)_0.9PbI₃ is a promising technique to improve the efficiency of Cs-doped perovskite solar cells.