A simulation-based comparative study of 2T and 4T perovskite/CIGS tandem solar cell configurations

The primary objective of next-generation solar cell technologies is to achieve higher power conversion efficiency (PCE) while maintaining long-term operational stability. Among the promising approaches to meet this demand, tandem solar cell architectures, particularly those combining perovskite and CIGS, have attracted significant attention owing to their complementary absorption spectra and potential for surpassing the efficiency limits of single-junction devices. This paper presents a comprehensive theoretical comparison between two-terminal (2T) and four-terminal (4T) configurations of perovskite/CIGS tandem solar cells by analyzing their performance characteristics and structural differences. The tandem designs considered in this study are based on a dual-junction layout. The front sub-cell consists of a perovskite film sandwiched between PCBM as an electron transport layer (ETL) and Cu 2 O as a hole transport layer (HTL). The rear sub-cell consists of a p-type CIGS absorber, integrated with a CdS buffer layer and a ZnO window layer to complete the bottom junction. The optoelectronic properties of each sub-cell are modeled and simulated under standard test conditions to evaluate the photovoltaic (PV) metrics for both 2T and 4T configurations. By comparing the interconnection schemes and operational mechanisms of the two architectures, this work highlights the trade-offs between fabrication complexity and device performance. The results provide valuable insights for guiding the design and optimization of high-efficiency tandem solar cells tailored for commercially feasible PV applications.