[Gd-Ho-Dy]:CsPbI1.8Br1.2 stable perovskite material as an absorber layer in photovoltaic devices, charge storage electrode, and an efficacious OER/HER catalyst

Current work presents the first report based on the all inorganic cesium lead halide perovskite material (CsPbI1.8Br1.2) doped with the rare earth oxides (gadolinium-holmium-dysprosium) leading to a synergistic [Gd-Ho-Dy]:CsPbI1.8Br1.2 semiconductor system. The developed system expressed impressive stability at ambient conditions for 28 days with the bandgap energy spanning between 1.65 and 1.69 eV. This perovskite material has characteristic ABX3 cubic black phase crystalline geometry with the 33.57 nm crystallite size. Fabricated thin films were highly compact with maximum coverage and were totally devoid of any pinholes. The perovskite solar cell device using [Gd-Ho-Dy]:CsPbI1.8Br1.2 as an absorber layer achieved an efficiency of 13.25% and open circuit voltage of 1.2 V. [Gd-Ho-Dy]:CsPbI1.8Br1.2/nickel foam electrode expressed an excellent charge storage potential with the specific capacitance of 406 F g−1 and lower series resistance of 0.58 Ω besides exhibiting stability for longer duration. [Gd-Ho-Dy]:CsPbI1.8Br1.2 is also a bi-functional electro-catalyst with the greater tendency for hydrogen evolution shown by a lower overpotential (ηHER) and Tafel values of 148 mV and 122.8 mV dec−1 than oxygen evolution. The endurance testing coupled with stability proved by other analyses is indicative of the candidature of developed material in different energy devices, systems, and applications.