Conversion Efficiency Of Strained Wurtzite In_xGa_1-xN/ZnSnN₂ Core/Shell Quantum Dot Solar Cell

Under the detailed equilibrium theory and effective mass approximation,the photoelectric properties of core/shell quantum dots（QD）are studied theoretically by variational method.Firstly,the photoelectric conversion efficiency,open-circuit voltage and short-circuit current density of strained wurtzite In_xGa_1-xN/ZnSnN₂ core/shell quantum dot solar cells with core,shell size and In content were theoretically studied and compared with the results without considering strain.The numerical results show that with the increase of core size,the open circuit voltage increases,while the short-circuit current density and photoelectric conversion efficiency decrease.With the increase of shell size and In composition,the open circuit voltage decreases monotonically,while the short-circuit current density and photoelectric conversion efficiency increase monotonically.In addition,strain will increase the band gap of QD resulting in an increase in open circuit voltage,while the photoelectric conversion efficiency and short-circuit current density decrease.Secondly,considering the influence of strain and external electric field,the band gap of wurtzite In_xGa_1-xN/ZnSnN₂ core/shell QD is calculated by variational method.Then,the relationship between the photoelectric conversion efficiency,open circuit voltage and short-circuit current density of the quantum dot solar cell with the core,shell size and In content is studied by using the detailed balance theory.Through numerical calculation,it is found again that the effects of core,shell size,In content and strain on the performance of solar cells are consistent with the previous ones.Under the action of external electric field,the band gap and open circuit voltage of wurtzite In_xGa_1-xN/ZnSnN₂ quantum dot solar cells show a decreasing trend,which leads to a significant increase in short-circuit current density and photoelectric conversion efficiency.Finally,the relationship between the band gap and photoelectric conversion efficiency of ZnSnN₂/In_xGa_1-xN/ZnSnN₂ multi-shell quantum dot solar cells with quantum dot size and In composition was studied.The numerical results show that with the change of quantum dot size and In composition,electrons will be localized in different regions of QD,and the corresponding band gap also has different variation rules,and then the photoelectric conversion efficiency also changes accordingly.