Interface passivation treatment enables GaAs/CNT heterojunction solar cells over 19 % efficiency

Without interface passivation, few technologies have realized carbon material-based GaAs heterojunction solar cells (HJSCs) with high power conversion efficiency (PCE) and long-term stability. Here, inorganic hole transport materials, such as CuSCN and CuI, were first created to address the issue of interface photo-generated carrier recombination in GaAs/carbon nanotube (CNT) HJSCs. The application of CuSCN and CuI passivation layer enables the PCE of GaAs/CNT HJSCs to be improved from 8.53 % to 17.22 % and 12.48 %, respectively. Furthermore, by employing the multifunctional WO3 film, which can serve simultaneously as a hole-blocking layer and an anti-reflection coating, to construct a collaborative optimization system, the cell performance can be further enhanced to 19.06 % and 15.53 %, respectively. Additionally, their stability has been significantly enhanced to 98.11 % and 111.5 %, respectively, which are much higher than that of the pristine HJSC (8.53 %). Especially, the high quality of Cu+-based passivation layer affords a fill factor (FF) of 80.21 %, which is a record for GaAs-based HJSCs. This work is a breakthrough as it presents a pioneering cross-generational concept for addressing the poor stability performance of carbon materials-based HJSCs.