Photobattery Architectures to Suppress Charge Recombination

Integrating solar energy conversion and storage into single-unit photobatteries offers compact energy supplies. However, achieving sufficient photovoltage to charge batteries without external bias remains a critical bottleneck for these devices. Here, we demonstrate that the photovoltage in Zn-ion photobatteries can be modulated and enhanced by selecting and structuring the photoactive materials strategically. Randomly dispersed electrode configurations are easy to manufacture, but suffer from charge recombination, yielding a negligible photovoltage of ~0.01 V in our experiments. In comparison, our proposed layer-by-layer design, integrating a solid-state dye-sensitized solar cell (DSSC) with an optimized spinel Zn–Mn oxide cathode, increased the photovoltage output to ~1 V under 1-sun illumination. This dramatic performance enhancement is achieved by better control over interfaces and charge transport, and establishes a strategy for improving the architecture of future photobatteries.