조도에 따른 단결정 실리콘 태양전지의 패시베이션 공정 최적화 연구

Abstract

Silicon dioxide (SiO2) is widely used to improve the surface passivation properties of silicon solar cells. In order to minimize solar cell potential induced degradation when PV module is installed outdoors, a silicon oxide film is widely used as an insulator. However, it has been confirmed through experimentation that solar cells using silicon oxide (SiO2) have a lower efficiency than solar cells without silicon oxide film (SiO2) in low illumination (<0.4 sun). Actually, the efficiency in the low illumination condition also affects the average power output per day because PV module mostly operates when the solar irradiation dose is less than 1 sun. In order to maximize the performance of PV module, the output at low intensity light level should also be considered. Shunt resistance (Rshunt) is known to cause a decrease in the solar cell efficiency in low illumination condition. PC1D simulation, we confirmed, was used to analyze parameters such as series resistance, parallel resistance, and surface recombination that affect the characteristics of the solar cell at low light intensity. In this study, we confirmed how affects the SiO2 layer on the low illumination properties of solar cells even though its higher efficiency at 1 sun. The silicon solar cells with SiNx/SiO2 bilayer and SiNx single film were fabricated and their characteristics were evaluated. Passivation characteristics were measured by using quasi steady-state photo conductance (QSSPC) to evaluate the minority carrier lifetime and the implied open-circuit voltage (iVoc), and capacitance-voltage measurement to analyze the fixed charges. The values of the shunt resistance and series resistance in solar cells with different passivation layers were compared, and the cause of the decrease in the efficiency under low illumination was also analyzed by fill factor calculation.