Development of a Perovskite Solar Cell Architecture for Opaque Substrates

Abstract

To date, substrate‐configuration metal‐halide perovskite solar cells (PSCs) fabricated on opaque substrates such as metal foils provide inferior efficiencies compared with superstrate‐configuration cells on transparent substrates such as glass. Herein, a substrate‐configuration PSC on planarized steel is presented. To quantify the differences between the two configurations, a 15.6%‐efficient n–i–p superstrate‐configuration PSC is transformed step wise into a substrate‐configuration cell. Guided by optical modeling, the opaque Au electrode is replaced by a transparent MoO 3 /thin Au/polystyrene dielectric–metal–dielectric electrode. The semitransparent device affords efficiencies of 15.4% and 11.4% for bottom and top illumination, respectively. Subsequently, substrate‐configuration PSCs with a metal bottom electrode are fabricated on glass and planarized steel, using a thin MoO 3 interlayer between the Au bottom electrode and the SnO 2 electron transport layer. The glass‐based substrate‐configuration cell provides 14.0% efficiency with identical open‐circuit voltage and fill factor as the superstrate cell. The cell on planarized steel reaches 11.5% efficiency due to a lower fill factor. For both substrate‐configuration cells, the lower short‐circuit current density limits the efficiency. Optical modeling explains this quantitatively to be due to absorption and reflection by the top electrode and absorption by the organic hole transport layer.