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Subject classification: 62.90.+k; 72.30.+q; 77.65.Dq; S.7.13 Using hydrodynamic model of homogeneous plasmas, an analytical study of parametric excitation of an acoustic wave in a transversely magnetised piezoelectric semiconductor has been reported. The electron momentum transfer collision frequency n is considered to be temperature dependent which is quite justified particularly at high intensity of the pump. The high-frequency electric field of the pump produces a nonlinear coupling between the generated acoustic and the electron-plasma waves which leads to an instability when a certain threshold value of the pump amplitude is exceeded. The presence of a transverse magnetic field is found to reduce considerably the threshold pump amplitude ðE th Þ for the onset of the said instability. The piezoelectricity of the medium below the threshold pump amplitude ðE 0 < E th Þ is found responsible for the damping of the acoustic wave, however, above the threshold pump amplitude ðE 0 > E th Þ the piezoelectricity of the medium proves to be boon for the acoustic wave and substantially enhances its growth.

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.