The power conversion efficiency (PCE) of the commercial solar cells have reached 23%, but still, solar power cannot be used as a standalone source of power without associated energy storage systems as they have to account for the diurnal (day and night) variation in sunlight. The problem of utilizing a battery to store solar power from panels is two-fold as it is both expensive and poses a scientific problem. The photogenerated electrons in a semiconductor have a low lifetime in the order of nano to microseconds, while the electrochemical processes during battery charging are slow (ms to seconds), leading to a loss of excited state carriers. An integrated photoelectrochemical (PEC) device-based architecture was therefore developed, with electrodes of the battery having dual functions of solar energy harnessing and storage leading to energy savings and cost benefits. Bromide based double perovskite material was utilized as a photoanode, given its facile synthetic protocol and long charge carrier lifetime.

The electrode architecture was optimized with careful consideration of the high surface area requirements of the battery and the carrier diffusion length of the double perovskite material. Redox mediators (active redox couples) which were employed for the battery were functionalized to suit the requirements of the MOC of the battery. The battery hence developed has demonstrated photo potential savings at a given C-rate. The fundamental charge transfer kinetics were probed at various SOC (State of Charge) of the battery using electrochemical techniques, and charge injection kinetics at the semiconductor electrolyte interface were monitored using excited-state lifetimes of the charge carriers as a probe.