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Herein, we have discussed the ethyl-ammonium based hybrid perovskite (viz. CH 3 CH 2 NH 3 PbI 3 or EAPbI 3) as the potential candidate material for the development of photovoltaic devices having low processing cost and high power conversion efficiency (PCE). To address the stability and environmental issues due to leaching of lead from MAPbI 3 , we urge to replace cation CH 3 NH 3 + (MA +) with an appropriate cation CH 3 CH 2 NH 3 + (EA +) and hope that the EAPbI 3 perovskite would prove to be a stable and eco-friendly photovoltaic absorber (PVA) material yielding high PCE. We have investigated physical properties like energy bandgap, electron density distribution and optical coefficients by FP-LAPW+lo and density functional theory (DFT). The present study reveals that EAPbI 3 has a direct energy bandgap of 1.55 eV with absorption coefficient exceeding 2 × 10 4 per cm, which confirms its suitability as PVA material. The dependence of thermoelectric (TE) coefficients on chemical potential and carrier concentration at various temperatures has also been discussed. We have also carried out the calculations of spectroscopic limited maximum efficiency (SLME) parameter (30.5%), and the thermodynamic (TD) properties in the realm of quasi-harmonic approximation. A detailed investigation on some of the properties of EAPbI 3 perovskite relevant to PVA material is being done for the first time, the present study may motivate researchers for more comprehensive theoretical and experimental investigations in search of stable and economically and environmentally viable PVA materials.

To address the instability issues arising due to leaching of lead in the extensively explored MPX perovskite, in this study, we suggest replacement of the cation CH 3 NH 3 + (M + ) with a larger cation CH 3 CH 2 NH 3 + (E + ). The proposed material EPX (CH 3 CH 2 NH 3 PbX 3 ; X = Br, Cl), due to the larger size of E + cation, is expected to offer increased hindrance to the movement of lead ions through the lattice and thereby reducing its degradation against heat and moisture. This investigation unfolds that EPBr has a direct energy band gap of 2.045 eV at R with absorption coefficient above 1.8 Â 10 4 cm À1 and SLME parameter as high as 21.5% for a film of thickness of 1 μm at ambient temperature of 300 K, which confirm its aptness as photovoltaic absorber material (PVA). The investigation also shows that n-type EPCl has a direct energy band gap of 2.668 eV with the figure of merit (ZT) exceeding 0.95 and Seebeck coefficient (S) more than 700 μV/K that reaffirm its suitability as thermoelectric (TE) material.