The global demand for sustainable and lightweight energy technologies continues to drive the development of advanced thin-film solar cells. Their potential for reduced material consumption, flexible integration, and scalable manufacturing makes them an essential component in the future of photovoltaics. However, despite decades of progress, thin-film silicon devices remain limited by material disorder and stability constraints, motivating the search for improved absorber and interface materials.

This research focuses on developing a predictive optical–electrical simulation framework for thin-film solar cells, capable of replicating real-world device behavior and guiding the design of next-generation architectures. The framework couples optical ray-tracing in GenPro4 with two-dimensional carrier-transport modeling in Sentaurus TCAD, allowing a realistic representation of textured interfaces, multilayer stacks, and lateral transport effects. The study begins with the calibration of single-junction amorphous silicon (a-Si:H) and nanocrystalline silicon (nc-Si:H) p–i–n cells against experimental data. These validated models are then combined into a tandem a-Si:H/nc-Si:H configuration, forming the optical and electrical foundation for further analysis.

Building on this baseline, the framework is extended to investigate flexible and hybrid device concepts. The transition from the rigid Asahi U-type glass substrate to a flexible configuration demonstrated the feasibility of lightweight devices, though efficiencies remained limited to approximately 10\% due to defect-assisted recombination and weak near-infrared absorption. To overcome these limitations, perovskite absorbers were explored. Single-junction perovskite devices with various hole-transport layers (HTLs) achieved simulated efficiencies up to 22%, with NiOx and nc-SiOx providing superior thermal and chemical stability. A hybrid a-Si:H/perovskite tandem reached 16% efficiency, benefiting from the protective silicon top layer but constrained by its lower current. A fully perovskite–perovskite (PVK/PVK) tandem employing inorganic and nc-SiOx HTLs achieved simulated efficiencies of 29%.

Finally, a detailed fill factor (FF) compensation study was conducted to quantify how current mismatch, recombination mechanisms, and electric-field distribution affect tandem performance. Five targeted case studies established design rules for stabilized operation through controlled mismatch, bandgap tuning, and optical optimization for a a-Si:H/nc-Si:H tandem solar cell.

Overall, this work delivers a unified simulation-based framework for the design and optimization of thin-film and hybrid tandem solar cells. The results provide fundamental insight into the performance limits of silicon and perovskite tandems and outline practical routes toward high-efficiency, lightweight, and manufacturable photovoltaic technologies.