Exploring Multifunction ZnO:Er3+/Yb3+ for High-Performance Dye-Sensitized and Lead-Free Perovskite Solar Cells Integration with Humidity Sensor

In the present work, multifunctional ZnO compounds are developed by doping erbium (Er³⁺) and ytterbium (Yb³⁺) through hydrothermal method at different pH conditions. X-ray diffraction studies confirm the phase formation and scanning electron microscopic images show the morphology changes with pH variation. The ZnO:Er³⁺/Yb³⁺ performs strong upconversion emissions at red and green wavelengths by excitation of 980 nm diode laser. Dye-sensitized solar cells (DSSCs) and lead-free MASnI₃-based perovskite solar cells (PSCs) are fabricated with synthesized materials. The co-sensitization with N719 and SPSQ1 dyes sandwiched with carbon-based counter electrode witnesses champion power conversion efficiency (PCE) of 13.83% with open-circuit voltage 0.74 V (for pH = 7 material), small tinny electric motor operated using fabricated DSSCs. Lead-free PSC is fabricated without any additives, yielding a PCE of 1.32%. The humidity sensor is developed by use of the synthesized material, integrated with DSSC/PSC, and acts as a self-powered device, exhibiting sensitive, stable performance. These results prove that the developed materials can have the potential for various applications including devices of the Internet of Things.