Inorganic CaMnO2.95 Perovskite for Solar Cell Applications

Md Samim Reza, Henam Sylvia Devi, Madhusudan Singh Functional Materials & Devices Laboratory, Department of Electrical Engineering, IIT Delhi, New Delhi, --, India

Perovskite materials have emerged as a promising class of materials for applications in solar photovoltaics due to their high efficiency and low cost relative to silicon-based solar cells. However, concerns about their long-term viability have been expressed due to their instability, toxicity, and processing issues. This work uses lead and halide-free inorganic perovskite and calcium manganese oxide (CaMnO2.95) as an alternative material for solar cell applications. CaMnO2.95 is inherently stable, nontoxic, and exhibits unique optoelectronic properties (bandgap 2.9 eV). Also, due to its abundantly available precursors, CaMnO2.95 renders a possible low-cost, sustainable material for solar cell applications. This perovskite is synthesized through an aqueous solution process followed by a heat treatment at 950℃ for 5 hrs without using organic solvents, making it nontoxic and environmentally friendly. Powder X-ray diffraction analysis confirmed the growth of orthorhombic CaMnO3 (PDF: 96-152-5995) with the most intense peak at 34.15° corresponding to the (211) plane. Field-emission scanning electron microscope image indicates the formation of interconnected nanoparticles of network structure with a porous nature. EDX confirmed the presence of Ca (22.1 ± 3.9), Mn (23.9± 6.4), and O (54 ± 9) in atomic %. The solar cell (1 x 1 mm2 area) with a structure of ITO/ ZnO/ CaMnO2.95/ NiO/ Mo layers reveals a power conversion efficiency of 2.02e-7%, a fill factor of 26.7%, an open circuit voltage of 115 mV, and short-circuit current density of 8.3 nA/cm2 (B2912A precision source/ measurement unit, Keysight, USA) under 1 sun illumination (Oriel LCS-100, Newport, USA). Additionally, using inorganic oxides such as ZnO as electron transport layers and NiO as hole transport layers has improved the stability of perovskite solar cells. This work demonstrates the potential of CaMnO2.95 as a promising inorganic perovskite material for solar cell fabrication.