CIGS PIN Junction Photosensitive Element

The CIGS absorption layer is segmented into three distinct layers with different doping types (p-type, intrinsic, n-type), forming a PIN junction structure. This segmentation allows each layer to contribute differently to light absorption and charge carrier generation, thereby improving overall light absorptivity and conversion efficiency while managing the increased structural complexity through systematic design

The patent employs a composite structure combining p-type CIGS, intrinsic CIGS, and n-type CIGS layers, potentially with a CdS buffer layer. This composite material approach optimizes the absorption spectrum by leveraging the complementary properties of different material compositions and doping states, achieving superior light absorption across a broader spectral range

Different copper contents are deliberately introduced into different layers of the PIN junction structure. The p-type layer has higher copper content optimized for light absorption, while the intrinsic and n-type layers have controlled copper contents suitable for their respective functions. This local quality differentiation allows each layer to be optimized independently, improving overall light absorptivity while distributing the manufacturing precision requirements across multiple layers rather than demanding uniform high precision throughout

The copper content parameter is systematically varied across the different film layers to optimize performance. By changing the copper concentration gradient from the p-type layer through the intrinsic layer to the n-type layer, the patent achieves enhanced light absorption in the high-copper p-type region while maintaining appropriate electrical properties in other regions, thereby balancing light absorptivity improvement with manageable manufacturing precision requirements