Dependence of photovoltaic parameters on grain size and density of states in n +–i–p + and p +–i–n + polycrystalline silicon solar cells

• Published in: Thin solid films 2007-11, Vol.516 (1), p.84-90
• Main Authors: Zebentout, B., Benamara, Z., Mohammed-Brahim, T.
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Energy; Exact sciences and technology; Grain size; Intergranular defects; Natural energy; Numerical simulation; Photovoltaic; Photovoltaic conversion; Physics; Polysilicon; Solar cells. Photoelectrochemical cells; Solar energy; Structure and morphology; thickness; Surface and interface electron states; Surface states, band structure, electron density of states; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.05.005

One-dimensional modeling of polycrystalline silicon (pc-Si) p +–i–n + and n +–i–p + homojunctions under AM1.5 light is presented. Single-crystalline grains separated by amorphous silicon transition zones are introduced to model the pc-Si structure. The usual density of states (DOS) with exponential band-tails and Gaussian-distributed deep levels is assumed in these transition regions. Effects of the grain size, the thickness of the undoped region and the DOS on the photovoltaic characteristics are presented. The calculation enables us to understand the very poor performance of the solar cells based on solid-phase-crystallized polysilicon processed at low temperature (< 600 °C). It gives the minimum value of the grain size and the maximum DOS to obtain acceptable photovoltaic performance.