9.05% HTM free perovskite solar cell with negligible hysteresis by introducing silver nanoparticles encapsulated with P4VP polymer

This study is a follow up to our previously published manuscript on improved power conversion efficiency in Perovskite solar cell using silver nanoparticles modified photoanode. Three more photoa nodes were fabricated which are: Ag@P4VP NPs mixed with perovskite layer (S2), Ag@P4VP NPs simultaneously mixed both in TiO2 and perovskite films (S3) and P25 NP simultaneously mixed both in TiO2 and perovskite absorber (S4) and their performances were investigated systematically. The performance, especially the photocurrent, and open circuit voltage of PSCs made of Ag@P4VP NPs were significantly affected. The champion device is S3, which shows enhancement in power conversion efficiency (PCE) from 3.80 to 9.05%, short circuit current density (Jsc) from 11.04 to 15.87 mA cm(-2), open circuit voltage (Voc) from 0.85 to 0.88 and fill factor (FF) from 0.41 to 0.65, which demonstrates -2.38 times improvement in PCE over the control device (C). When Ag@P4VP NPs was mixed with TiO2, PCE of 5.69%, Jsc of 12.61 mA cm(-2), Voc of 0.88 V and FF of 0.51 were achieved, which shows similar to 1.50 times improvement over the performance of the reference cell. Also, when Ag@P4VP NPs was mixed with the perovskite layer, PCE of 8.08%, Jsc of 14.18 mA cm(-2), Voc of 0.89 V and FF of 0.64 were achieved, which shows similar to 2.13 times improvement over the performance of the pristine device. The addition of Ag@P4VP NPs enhanced exciton generation and dissociation, encouraging charge separation/transfer, as well as reducing quenching losses. For the hysteresis test, it was found that the devices with Ag@P4VP NPs have almost identical J-V curves with negligible hysteresis, which is attributed to the significant reduction of the trap density of the perovskite film when Ag@P4VP NPs is incorporated to fill the pores with high trapping rate. We however observed hysteretic behavior in devices C and S4, which makes it difficult to estimate the real PCE.