Bandgap Engineering Enhances the Performance of Mixed-Cation Perovskite Materials for Indoor Photovoltaic Applications

Indoor photovoltaics (IPVs) are attracting renewed interest because they can provide sustainable energy through the recycling of photon energy from household lighting facilities. Herein, the Shockley-Queisser model is used to calculate the upper limits of the power conversion efficiencies (PCEs) of perovskite solar cells (PeSCs) for two types of artificial light sources: fluorescent tubes (FTs) and white light-emitting diodes (WLEDs). An unusual zone is found in which the dependence of the PCEs on the bandgap (E-g) under illumination from the indoor lighting sources follows trends different from that under solar irradiation. In other words, IPVs exhibiting high performance under solar irradiation may not perform well under indoor lighting conditions. Furthermore, the ideal bandgap energy for harvesting photonic power from these indoor lighting sources is approximate to 1.9 eV-a value higher than that of common perovskite materials (e.g., for CH3NH3PbI3). Accordingly, Br- ions are added into the perovskite films to increase their values of E-g. A resulting PeSC featuring a wider bandgap exhibits PCEs of 25.94% and 25.12% under illumination from an FT and a WLED, respectively. Additionally, large-area (4 cm(2)) devices are prepared for which the PCE reaches approximate to 18% under indoor lighting conditions.