Toward ultra-thin and full functional perovskite solar cells by broadband light scattering management and efficient interfacial modification

Abstract Decreasing the thickness of perovskite absorption layer is significant for obtaining semi-transparent, tandem and flexible photovoltaic devices with high performance. However, the light harvesting would be influenced due to the limited absorption. Introducing plasmonic metal nanoparticles into perovskite solar cells (PSCs) is regarded as a promising approach on the development of ultra-thin PSCs. In this work, gold nanostars (Au NSs) with strong local electromagnetic field and SnO2 surface modification layer were successfully incorporated into ultra-thin PSCs. This design increased light harvesting and carrier transporting. Furthermore, we systematically investigated the plasmon effect of Au NSs on the power conversion efficiency (PCE) of the PSCs with different thicknesses of the perovskite layer and observed that the deceased thickness of perovskite layer led to more intense PCE improvement as the same Au NSs were introduced. The ultra-thin PSCs with 250-nm perovskite layer show a PCE improvement from 15.34 to 18.50% after Au NSs/SnO2 modification, accounting for a maximum enhancement factor of 20.60%. Simultaneously, the modified PSCs with 400-nm perovskite layer exhibit a best reported PCE of 20.06% for the plasmonic PSCs, with an enhanced factor of 13.70% and enhanced light stability. More importantly, flexible, large area and semi-transparent PSCs were also achieved. The flexible devices show more than 90% of their initial PCE values after 100 bending cycles. Our result promises a facile way for developing efficient, flexible and semi-transparent PSCs with ultra-thin absorption layer.