High-efficiency thin film ZnMgO/ZnO solar cell simulation approach: Temperature dependency, BSF and efficient small signal analysis

Small signal analysis for Al/ZnO/c-Si/Ag heterojunction solar cell structure is investigated in this simulation work. Effect of signal frequency, device temperature and junction interface defect state density on the junction diffusion capacitance and device conductance are thoroughly examined. Built in potential measurement highlights variation from 0.8 to 2.1 eV for the range100 Hz to 8 MHz which showing a good agreement with the practical value. Low temperature (10-100 K) conductance measurement at 2 V biasing results a localised Fermi level state density 9.54 × 1040 cm−3eV−1and evidences variable range hopping conduction. Excellent improvement of short circuit current density and efficiency is observed using MgxZn1-xO window layer. The increase in short circuit current density and efficiency due to the use of the window layer are 31.85 mA cm−2 and 19.17% respectively. For all the study illumination of 400 nm monochromatic light with photon flux 2.8 × 1017 cm−2s−1 and spectral width 10 nm are applied. Uses of 400 nm light is due to study of temperature dependency on open circuit voltage of solar cell. Using 1000 wt/m2 the efficiency of solar cell is enhanced from 19.88% to 23.15%.