Indoor organic solar cells for low-power IoT devices: recent progress, challenges, and applications

In the last few years, organic solar cells have emerged with potential applications in abundant low-power indoor Internet of Things devices, such as smart watches, calculators, remote controls, and other devices. Since indoor light intensity is much weaker than standard 1 sun illumination, effective utilization of indoor photons is crucial due to the significant spectral mismatch and weaker light intensity of indoor light compared to the standard 1 sun illumination. Considerable efforts have been devoted to improving indoor solar cells and module power conversion efficiency in the past few years using wide bandgap acceptor and donor molecules with complementary absorption spectra, well-matched energy levels, devices engineering, etc., and the PCE has reached more than 31%. To further optimize the performance of the materials and devices, researchers are working on several key challenges, such as synthesizing new materials for the indoor active layer with well-matched indoor absorption spectra, devices with large open-circuit voltages with low energy loss, and long-term stability under indoor conditions, and should be considered carefully for further improvement in the indoor performance. This review will summarize and discuss the recent progress in optimizing indoor photovoltaic materials and devices and the key strategies to optimize indoor-OSCs characteristics. In the last few years, organic solar cells have emerged with potential applications in abundant low-power indoor Internet of Things devices, such as smart watches, calculators, remote controls, and other devices.