Numerical simulation of graphene/Ag2ZnSnSe4 induced p-n junction solar cell

Ag2ZnSnSe4 is an n-type semiconductor with a suitable bandgap of 1.4 eV. In the present study, a graphene/Ag2ZnSnSe4 induced p-n junction thin film solar cell is proposed and the physical mechanism and performance influencing factors of the solar cell are simulated and analyzed by using the wxAMPS software. The simulation results show that when a high work function graphene contacts an n-type Ag2ZnSnSe4 semiconductor, the energy band of the Ag2ZnSnSe4 absorber layer bends upward, meanwhile a p-type Ag2ZnSnSe4 inversion layer is induced on the surface of n-type Ag2ZnSnSe4, therefore the p-type Ag2ZnSnSe4 and n-type Ag(2)ZnSnSe(4)2 ZnSnSe4 form an induced p-n homojunction. It is found that the work function of graphene and back contact significantly influence the photogenerated carrier separation, transportation and collection. The graphene work function should be 5.5 eV and the work function of back contact should not be greater than 4.4 eV, which is beneficial to the improving of the device performance. The doping concentration of Ag2ZnSnSe4 absorber mainly affects the short-circuit current of the device, however, the defect density of Ag2ZnSnSe4 absorber affects the whole device performance. When the work function of graphene and back contact are 5.5 eV and 3.8 eV, the doping concentration and defect density of Ag2ZnSnSe4 absorber are 10 16 cm(-3) and 10(14) cm(-33), respectively, the conversion efficiency of the graphene/Ag2ZnSnSe4 induced p-n junction thin film solar cell can reach 23.42%. These simulation results provide the idea and physical explanation for designing a novel type of solar cell with high efficiency and low cost.

Automated summary

In this study, a graphene/Ag2ZnSnSe4 induced p-n junction thin film solar cell is proposed and simulated to analyze the performance influencing factors of the device. The results show that the work function of graphene and back contact significantly affect the carrier separation, transportation, and collection, while the doping concentration and defect density of the Ag2ZnSnSe4 absorber also play a crucial role in determining the device efficiency. By optimizing the work function and properties of the materials, a high-efficiency and low-cost solar cell can be designed.