Efficient and stable perovskite solar cell through the interfacial engineering: Experiment and computational investigations

Pure phase LaMnO3 (LMO) and NiCo2O4 (NCO) are synthesized via. the conventional sol-gel route to use as absorber and hole transport materials respectively in the perovskite solar cell (PSC) device. The pure phase cubic crystal structure of LMO with space group Pm-3m and face centred cubic spinel crystal structure of NCO with space group Fd-3m are verified through the powder XRD data with the particle size of 10.8 nm–26.5 nm for pure LMO and 2.60 nm–30.1 nm for pure NCO. FESEM-EDS micrographs and FTIR spectra also confirm the phase formation of the LMO and NCO nanomaterials. The mean particle size using FESEM is calculated for LMO (∼73.44 nm) and NCO (∼19.62 nm) respectively. The diffuse reflectance spectroscopy (DRS) UV–Vis is yielding direct optical band gap value of 2.40 eV for LMO and 1.78 eV for NCO, respectively. The band gap of LMO is also calculated using DFT analysis and compared with the present experimental as well as available literature values of experiment and theory. With the observed initial parameters of the experiment and available literature, solar simulation is performed on the designed device of PSC heterostructure FTO/ETL/LMO(Absorber)/NCO(HTL)/Au. After the optimization with the variation in the various device parameters such as thickness of different layers, defect density, band gap, electron affinity, ETLs, series resistance, and temperature, the best performance photovoltaic parameters are observed: Voc = 1.16 V, Jsc = 15.34 mA/cm2, FF% = 72.72%, and PCE% = 12.95% with the SnO2 as ETL. Subsequently, the capacitance-voltage (C–V), Mott-Shottkey (MS; 1/C2–V) and conductance-voltage (G-V) measurements also performed on this device via simulation and confirmed the deep defects in the final optimized PSC device. Temperature dependent C-f characteristics and voltage dependent Nyquist plots confirm the thermally developed dielectric constant and enhanced conductivity with the reduced impedance of the PSC device.