We focus on the commonly observed S-shaped anomaly, or S-kink, in the I-V characteristics of silicon-based solar cells. Three representative material silicon-based photovoltaic systems were studied, including: crystalline silicon (c-Si), multi-crystalline silicon (mc-Si), and amorphous silicon (a-Si: H), to systematically analyze the microscopic physical mechanisms of the S-kink under different device structures and interface conditions. By introducing concepts such as energy band engineering at interfaces, interface-state-induced potential barriers, charge accumulation, and carrier recombination behavior, the study reveals that band misalignment, Fermi level pinning, and high-density defect states are the fundamental causes of carrier transport barriers leading to S-kink. In terms of teaching practice, this work proposes integrating the S-kink phenomenon into the college physics experiment curricula, and establishes an inquiry-based instructional model that combines experimental measurement, theoretical modeling, and numerical simulation. The methodology aims to cultivate the students' ability to infer microscopic mechanisms from macroscopic observations, build quantitative models, and utilize simulation tools for parameter extraction and device performance optimization. Through cross-comparison among different material systems and experimental conditions, the students can develop a comprehensive understanding including device structure, material properties, interface physics, and electrical output response. The study deepens the physical insight into non-ideal behaviors in the photovoltaic devices and offers a practical and pedagogical framework for the reform of advanced college physics experiment courses.
Xie et al. (Sun,) studied this question.