An All Solution-Processed Lead Halide Perovskite-BiVO4 Tandem Architecture Delivering STH of 2.5%

Abstract

We report an all solution-processed tandem water splitting device composed of a BiVO4 photoanode and a single-junction lead halide perovskite solar cell (CH3NH3PbI3). In this configuration, the surface of BiVO4 photoanode is in contact with water for water oxidation reaction, and the lead halide perovskite solar cell is situated behind the BiVO4 photoanode to supply additional photovoltage to drive water reduction reaction through a Pt gauze. This architecture allows efficient solar photon management, with BiVO4 photoanode selectively harvesting high energy photons (< 500 nm) and lead halide perovskite solar cell selectively harvesting low energy photons (500 to 800 nm) in a single-pass excitation. By modifying the surface of BiVO4 photoanode with an earth-abundant cobalt phosphate thin film, we showed that this design is capable of delivering solar to hydrogen conversion efficiency (STH) of 2.5 % under AM 1.5G illumination at neutral pH. Our results demonstrate the potential of using low-cost, single-junction lead halide perovskite solar cells to assist n-type metal oxides to carry out bias-free photocatalytic water splitting. The unique photoanode-photovoltaic design offers opportunities to explore other semiconducting materials with extended visible light absorption ability to further improve the STH.