# CZTSe-Based Solar Cell Performance Improvement Using the CSLO Technique
## 1 Introduction
In this regard, many research projects with various techniques have been reported. For instance, changing the height of the pillars results in an efficiency increase in devices consisting of nanopillars of CdTe coated with a very thin layer of CdS. [23]. In fact, these methods can be used to maximize light absorption and performance optimization. Additionally, [PERSON] et al. [24] utilized screen-engineered field effect Cu\({}_{2}\)O-based solar cells to enable low-cost and high-efficiency cells. In addition, an optimization of InGaP/GaAs single-/multi-junction solar cell performance was presented by [PERSON] in [25] to boost the photovoltaic conversion efficiency, in which when the tunnel junction and back surface field design was optimized, the cell's photovoltaic performance was increased. [PERSON] et al. [26] proposed four-junction solar cells based on germanium wafer bonding. The presented structure provided high efficiency, due to employing germanium which required an optimized Ge cell with rear-side passivation and a mirror. On the other hand, germanium is an indirect semiconductor that impacts light absorption. In another study [27], the proposed solar cell employed a combination of the Liquid Phase Crystallized Silicon and Perovskite techniques to produce a low-cost and high-performance device. Moreover, different bandgap energies in multi-junction solar cells will change under real conditions due to temperature variations; this phenomenon causes higher sensitivity to spectral changes because of the sun's movement in the sky and atmospheric conditions. [PERSON] et al. [28] demonstrated the usage of the CdS as a buffer layer in CZTSSe-based solar cells, which significantly improved the device's overall performance. Additionally, the solar cell proposed by [PERSON] et al. [29] had optimized absorbent layer doping and an appropriately chosen metal contact, thereby considerably reducing the recombination rate. In another paper, [PERSON] et al. [30] used CZTSSe-based SnS thin films for improving the conversion efficiency of solar cells. As mentioned previously, the main advantages of CZTSSe-based solar cells are their non-toxic properties--in contrast to Copper Indium Gallium Selenide (CIGS) solar cells--that they use earth-abundant, low-cost materials, and their structural simplicity [2; 5]. These advantages make CZTSSe a desirable material for photovoltaic applications. Although the improved performance of CZTSSe-based solar cells has been extensively studied, varying the layer specifications has been investigated by researchers less often. In this paper, the proposed CZTSSe-based solar cell employs the CSLO technique (CZTSSe- based Solar cell Layer Optimization) to achieve high efficiency with a noncomplex structure by varying the layer specifications, such as selecting the optimum layer thickness and doping concentration of the layers. The CSLO technique in SILVACO provides the optimum thickness and doping concentration of layers by varying the layer specifications. In this technique, the absorber layer is divided into two layers with different doping concentrations and materials. In addition, the absorber layer is divided into two layers with different doping concentrations, as shown in Figure 1. In fact, by implementing a p+pn junction, the number of holes and electrons will be increased on two sides of the junction, resulting in an increase in the generated current, a decline in the recombination rate, and an improvement in the efficiency of the solar cell in comparison to conventional ones. Similarly, the p+ layer and the nearby backside contact made a junction with a more linear response than a p-type layer (with a lower doping concentration), which led to performance enhancement. In this technique, the p+ layer provided an extra field, causing lower carrier recombination by transmitting more electrons to the absorber layer and collecting more carriers at the contacts simultaneously. Furthermore, the Silvaco TCAD ATLAS tool was used to measure the performance parameters.