Alternative surface texturing, passivation and charge selective contacts for crystalline silicon solar cells

2022-9-2
Sarıgül Duman, Elif
This study focuses on realizing three crucial steps in silicon solar cell manufacturing by utilizing alternative methods. Black silicon is of interest as an alternative surface texturing method for achieving enhanced light trapping and reduced reflection of the crystalline silicon solar cell. Black silicon fabrication via the inductively coupled plasma reactive ion etching method and the feasibility of black silicon solar cells were investigated. Reduced optical reflectance was achieved with a total weighted average reflectance as low as 2.3% with superior uniformity. By the investigations conducted to comprehend potential loss mechanisms in the silicon solar cells, black silicon PERC solar cell was realized with a power conversion efficiency of 19.7%. As an alternative silicon surface passivation method, ozone-based thermal atomic layer deposited aluminum oxide films were investigated. The influence of oxidant precursors in atomic layer depositions was examined regarding silicon surface passivation quality. Its potential applications, such as the passivation of crystalline silicon surfaces in PERC solar cells, were discussed. A simplified process flow for the rear passivation stack of PERC solar cell was proposed by eliminating the out-gassing step. Superior silicon surface passivation was demonstrated by aluminum oxide/silicon nitride stacks with an implied open-circuit voltage of 730 mV. Considering the intrinsic drawbacks of doped amorphous films and complex deposition requirements, carrier selective contact formation by a low-cost, vacuum-free method was proposed. Organic self-assembled organic molecules, namely FOPA and 2PACz, were investigated as novel and alternative electron-selective contact in silicon heterojunction solar cells. The stability of organic films under ambient air was demonstrated. Silicon heterojunction solar cells with organic molecule modified electron-selective contacts were developed, resulting in a power conversion efficiency of 16.5%.

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Citation Formats
E. Sarıgül Duman, “Alternative surface texturing, passivation and charge selective contacts for crystalline silicon solar cells,” Ph.D. - Doctoral Program, Middle East Technical University, 2022.