This research presents a design and analysis of a tandem solar cell, combining thin film wide bandgap
Sb2S3 (1.72 eV) and narrow bandgap CIGS (1.15 eV) for the top and bottom sub-cells, respectively.
The integration of all thin film layers enhances flexibility, rendering the tandem solar cell suitable for
applications such as wearable electronics. To optimize the power conversion efficiency (PCE) of the
tandem solar device, advanced technology computer-aided design (TCAD) simulation tools are
employed to estimate loss mechanisms and fine-tune parameters for each layer. An experimentally
validated optoelectronic model is introduced, calibrated and validated against fabricated reference
solar cells for the individual top and bottom cells. The calibrated model is then utilized to propose
optimization routines for the Sb2S3/CIGS tandem solar cell. The initial tandem cell exhibits a JSC of
15.72mAcm−2 and a PCE of 15.36%. The efficiency drop in the tandem configuration is identified
primarily in the top cell. Asystematic optimization process for the top cell is initiated, exploring
various configurations, including HTL-free and ETL-free setups. Moreover, an np homojunction
structure for the top cell is proposed. Optimization routines are applied that involve determining
optimal thickness and doping concentration of the n-layer, investigating the effect of p-layer doping
concentration, and exploring the influence of the work function of the front contact. As a result, the
tandem cell efficiency is significantly improved to 23.33% at the current matching point (CMP), with a
JSC of 17.15mAcm−2. The findings contribute to the advancement of thin-film tandem solar cell
technology, showcasing its potential for efficient and flexible photovoltaic applications. |
