2D perovskite photovoltaics are fabricated with ammonium cations to enlarge the bandgap of the active materials. A power conversion efficiency larger than 30％ has been achieved and the device stability is also improved after the use of 2D materials. The results indicated that 2D perovskite materials are ideal for practical indoor applications.
With sufficient power supply, a children healthcare system based on IoT technologies is demonstrated. The indoor photovoltaic module prepared with 2D perovskite materials can supply sufficient power to a beacon under normal indoor lighting conditions. The battery-less beacon consists of temperature and moisture, and position sensors, which can be used for monitoring the physical condition of a baby.