Semitransparent perovskite solar cells with ultrathin silver electrodes for tandem solar cells

Abstract

Tandem solar cells with top perovskite solar cells (PSCs) have attracted great attention due to the rapid progress in power conversion efficiency (PCE). Ultrathin silver (Ag) metals with low percolation threshold are promising candidates as transparent electrodes for semitransparent PSCs. In this work, continuous Ag films with percolation threshold lower than 6 nm were realized through Cu seed layer, which guaranteed not only excellent conductivity but also broadband transparency. As a result, semitransparent PSCs with 6 nm Ag electrodes exhibited PCE of 14.5%, maintaining 88% performance of the opaque PSCs. Moreover, the average transmittance of semitransparent PSCs in the range of 800–1200 nm was improved to 58.6% using zinc oxide as optical coupling layer, promising near infrared light absorption by bottom solar cells. Ultimately, four-terminal tandem solar cell using semitransparent PSC and homogenous crystalline silicon solar cell was demonstrated. Furthermore, the strategies of using 5 nm Ag electrodes combined with Ag grids, and optical coupling layers with higher refractive index, were suggested to further increase the PCE of tandem solar cells. The proposed ultrathin Ag transparent electrodes are ease of fabrication as well as good optoelectrical properties, which are promising for application in semitransparent PSCs and tandem solar cells.