CdZnTe thin films as proficient absorber layer candidates in solar cell devices: a review

Abstract

The energy crisis has become the greatest global challenge in this era of cutting-edge technology, driving researchers to utilize novel renewable energy resources via solar cells to satisfy the energy demand. To date, the popular silicon solar cell technology has achieved a power conversion efficiency (PCE) of more than 26% at the laboratory scale and is superior to other technologies with a commercial panel efficiency in the range of 14–20%; however, it is very costly. Alternatively, organic solar cell engineering is cheaper but the resulting PCE is very low. Second-generation technology is dominated by CdTe and CIGS solar cells, having an efficiency of more than 22%. In 2009, perovskite solar cell technology was invented with a PCE of 3.8%, which has now reached up to 25.7%. Considering the Shockley–Queisser limit, the maximum efficiencies of these technologies may be around 30% for single-junction devices with 33% for GaAs solar cell devices. Currently, to meet the global energy demands, high-efficiency solar cell devices are required that can surpass the limit for single-junction devices, which can be achieved by tandem structures. In this case, the CdZnTe (CZT) material is a promising candidate for the fabrication of solar cells, where CdZnTe thin films are applied as absorber layers in devices possessing a tandem architecture. Furthermore, the physical properties of these films can be tuned by varying factors such as thermal annealing, Zn concentration and chloride treatment. Accordingly, this review presents an overview of CdZnTe as a suitable absorber material in solar cell devices together with the development employing different techniques, impact of thermal annealing and chloride treatments and variation in composition on the physical properties and performance of devices. Also, future road map is presented with recommendations to surpass the PCE limit through tandem designs.