Understanding and Engineering the Perovskite/Organometallic Hole Transport Interface for High-Performance p–i–n Single Cells and Textured Tandem Solar Cells

Abstract

To address challenges in perovskite solar cells integrated with textured silicon, we developed a multilayer structured hole transport layer (HTL) on the basis of organometallic copper phthalocyanine (CuPc): N,N,N′,N′-tetra[(1,1′-biphenyl)-4-yl](1,1′:4′,1″-terphenyl)-4,4″-diamine (TaTm)/CuPc/Al₂O₃. Thermally evaporated CuPc provides stability and desired wettability for the perovskite solution. We identified a unique surface-bulk recombination pattern at the CuPc/perovskite interface that results in a high fill factor (FF = 87%) but a low open-circuit voltage (V_oc) due to surface recombination losses. TaTm enhances electron blocking, while Al₂O₃ forms a porous insulator contact that mitigates nonradiative recombination. Double-sided optimization of CuPc with TaTm and Al₂O₃ effectively reduced the surface recombination without compromising the carrier extraction efficiency. This HTL structure achieved PCE values of 22.5% and 24.5% for 1.65 and 1.54 eV perovskite in p–i–n single cells and 28.9% in textured silicon/perovskite tandem cells. The conformal and wettable HTL structure promotes uniform perovskite coating, thereby reducing issues, such as pyramid puncturing, on textured Cz-Si wafers from production lines.