High-Performance\nand Stable Perovskite/Organic Tandem\nSolar Cells Enabled by Interconnecting Layer Engineering

Perovskite/organic tandem solar cells (PO-TSCs) have\nrecently attracted\nincreasing attention due to their high efficiency and excellent stability.\nThe interconnecting layer (ICL) is of great importance for the performance\nof PO-TSCs. The charge transport layer (CTL) and the charge recombination\nlayer (CRL) that form the ICL should be carefully designed to enhance\ncharge carrier extraction and promote charge carrier recombination\nbalance from the two subcells. Here, we propose an effective strategy\nto optimize the ICL by using [2-(9<i>H</i>-carbazol-9-yl)ethyl]phosphonic\nacid (2PACz) to modify the poly(3,4-ethylenedioxythiophene):polystyrenesulfonate\n(PEDOT:PSS) as the hole transport layer (HTL) in the ICL. It is found\nthat the coverage state of 2PACz on the PEDOT:PSS significantly affects\nthe performance of PO-TSCs and can be regulated by adjusting the concentration\nof the 2PACz solution. The PEDOT:PSS/2PACz structure facilitates effective\ncharge carrier extraction from the organic solar cells to the CRL.\nHerein, for the PO-TSCs, this strategy results in an efficient and\nbalanced charge carrier recombination in the ICL and also allows a\nthinner PEDOT:PSS with reduced parasitic absorption. As a result,\nthe PO-TSC achieves a power conversion efficiency (PCE) of 25.26%,\nmuch higher than the control device (PCE of 23.57%), and better stability.\nThis work demonstrates an effective approach to achieving high-performance\nPO-TSCs through ICL engineering.