| Summary: | 碩士 === 國立中山大學 === 電機工程學系研究所 === 103 === The concept of locating the emitter and electrodes of a solar cell at the rear thereby creating an interdigitated back contact has great potential to achieve higher power conversion efficiency in the future market. In this paper, we propose a new heterojunction with intrinsic thin-layer (HIT) structure with interdigitated back contacts and rear trench-shape body, called as TS-IBC solar cells. The conventional HIT solar cell is limited by the optical losses on the front grid caused crystalline silicon substrate cannot absorb a part of sunlight. In this paper, having all contacts on the rear side to form interdigitated back contact, which can overcome the shadowing loss. Furthermore, the crystalline silicon substrate of the new cell is etched into trench shape. This extended trench shape can generate more photo-generated carriers to achieve higher short-circuit current density and the emitter can allow more minority carriers being collected. The back surface field can also extend through the extended trench shape body to accelerate carrier transmission resulting in carrier recombination was reduced. So, the TS-IBC solar cell of crystalline silicon heterojunction structure can achieve higher power conversion efficiency. Several key factors affecting the power conversion efficiency of the solar cell, such as front surface field, trench depth, trench width ratio, film thickness, surface recombination velocity, pitch and temperature are also simulated and investigated. The TS-IBC structure is optimized by using TCAD software. Then, we found that this new structure has a higher short-circuit current density which is about 6.03 % higher than that of the conventional IBC cell. Also, the new TS-IBC structure achieves power conversion efficiency 27.76 % which is about 7.79 % better than that (25.6 %) of the conventional IBC HIT solar cell.
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