An Efficient Solution‐Processed Interconnecting Layer for Large‐Area Tandem Organic Solar Cells

Abstract

Interconnecting layer (ICL) is a key part of the tandem organic solar cells (OSCs) to achieve high efficiency. The ICLs of efficient inverted nonfullerene OSCs are complicated that comprise vacuum‐deposited MoO3, solution‐processed ZnO, and an additional thin silver (or PEDOT:PSS) film in between. Herein, an efficient fully solution‐processed ICL is first reported that comprises a PEDOT:F layer and a ZnO layer. The PEDOT:F is short for poly(3,4‐ethylenedioxythiophene):perfluorinated sulfonic acid ionomer that is alcohol dispersed and has a work function of 5.6 eV for hole collection. The ZnO is used for electron collection. The PEDOT:F/ZnO has a conductivity of 2.28 × 10−3 S cm−1 which can play a recombination zone. The solution‐processed ICL of PEDOT:F/ZnO has been validated in both two‐junction and triple‐junction solar cells. The tandem cells show high fill factor (FF) of 76–80% and high open‐circuit voltage (VOC) which is nearly the sum of the single‐junction OSCs. The PEDOT:F/ZnO ICL has also been used to fabricate large‐area tandem organic module (15.48 cm2) that shows a VOC of 10.25 V, FF of 75.1%, and a power conversion efficiency of 13.24%. The PEDOT:F/ZnO is a promising ICL for high‐performance tandem OSCs.