Pivotal Role of Middle Subcell Thickness on the Performance of Triple‐Junction Tandem Polymer Solar Cells

Abstract

Making multijunctions in organic solar cells with solution‐processed polymeric bulk heterojunction (BHJ) layers, i.e., tandem polymer solar cells (PSCs), has been one of the state‐of‐the‐art approaches for the last two decades. Tandem PSCs can overcome the single‐junction Shockley–Queisser limit by improving light absorption as they can exploit the polymeric BHJ layers with poor charge carrier mobility as subcells with limited thickness. Herein, 13% efficient triple‐junction tandem PSCs with a nanocrated hybrid interconnection layer (hICL) can be achieved by controlling the BHJ thickness (60 nm) of middle subcells is demonstrated. The open‐circuit voltage and fill factor (FF) of the optimized triple‐junction tandem PSCs reach 2.14 V and 74.3%, respectively. The present approach of middle subcell thickness control, using the reproducible hICL‐based multilayer stacking technology, delivers a promising way to further extend the number of junctions leading to high efficiency tandem PSCs with enhanced open‐circuit voltages and FFs.