Tandem Silicon Photovoltaic/Hydrovoltaic Devices for Synergistic Utilization of Solar Energy

In conventional photovoltaic (PV) devices, sub-bandgap photons remain unutilized, contributing to heat accumulation and temperature-induced efficiency losses. Here, we present a tandem silicon photovoltaic/hydrovoltaic (PV/HV) device designed for synergistic and highly efficient solar energy utilization. In this configuration, photons with energies above the silicon bandgap drive PV electricity generation, while the remaining solar energy is converted into thermal energy to facilitate water evaporation, enabling HV electricity generation and water purification. A thermally conductive pathway, formed by silicon and copper, ensures efficient heat transfer from the heat-averse PV device to the heat-utilizing HV device, synergistically improving the performance of each module. As a result, the equivalent power output under 1 sun illumination is improved from 200 ± 3 W·m^-2 of a single PV device to 205 ± 3 W·m^-2 of the tandem PV/HV devices. Moreover, the tandem devices can generate purified water at a rate of 0.78 ± 0.05 kg·m^-2·h^-1. This work presents an effective strategy for the comprehensive and efficient utilization of solar energy.