A triple-junction perovskite/silicon tandem solar cell has achieved a world record power conversion efficiency of 27.1% across a solar energy absorption area of 1 cm². The notable performance and stability of this photovoltaic device is attributed to the inclusion of cyanate in its structure.

The solar cell developers sought to expand the energy range and improve power conversion efficiency of triple-junction perovskites by using cyanate, a novel pseudohalide, as a substitute for bromide. The tandem devices were assembled by stacking a perovskite solar cell and a silicon cell to form a dual-junction half-cell. This afforded an ideal structure for attaching the cyanate-infused perovskite component. The resulting cells were demonstrated to attain an open-circuit voltage of 1.422 V compared to 1.357 V for conventional perovskite solar units, with a significant reduction in energy loss.

After continuous operation at maximum power for 300 hours under controlled conditions, the newly minted cells remained stable and functioned above 96% capacity. The complex structure described in Nature posted a certified world-record efficiency of 27.1% from an accredited independent photovoltaic calibration laboratory.

Researchers from Beijing University of Technology (China), National University of Singapore, Suzhou Maxwell Technologies Co. (China) and the Technical University of Munich (Germany) contributed to this development.