Enhancement of kesterite solar cells using a carbon nanotube as a back surface field layer

We investigated and optimized a new design structure for CZTSSe thin film solar cells, incorporating a single-walled carbon nanotube (SWCNT) as the back surface field layer. This technique enhances efficiency by minimizing carrier recombination at the device's back surface and enhancing the collection of photo-generated carriers.

In this study, the Solar Cell Capacitance Simulator - One Dimension (SCAPS-1D) simulator was used to investigate the enhancement of the performance of CZTSSe-based solar cells by incorporating a carbon nanotube back surface field (BSF) layer in the basic AZnO/i-ZnO/n-CdS/CZTSSe/Mo structure device. The cell performance simulations were studied by examining the different optoelectronic properties, such as the thickness of the absorber and the BSF layer, and the bulk and interface defect densities. The results demonstrate that carefully optimizing these parameters can significantly enhance photovoltaic performance. Specifically, the output parameters showed marked improvements: an open circuit voltage (V_OC) of 0.81632 V, a short circuit current density (J_SC) of 46.87 mA/cm², a fill factor (FF) of 76.38 %, and an efficiency (PCE) of 29.20 % when SWCNT was used as the BSF layer. This novel application of SWCNTs significantly reduces recombination losses, leading to improved carrier collection and enhanced efficiency in solar cells. The simulation results further demonstrate that using SWCNT material as a BSF layer could enable the fabrication of inexpensive and highly efficient CZTSSe-based thin-film solar cells.