High performance amorphous silicon oxide thin film solar cells fabricated at very low temperature

Abstract

Present thin film solar cells with hydrogenated amorphous silicon oxide (a-SiO:H) as an absorber suffer from low fill factor(FF) of 61~64 [%] in spite of its benefits related to high open circuit voltage (Voc). Since degraded quality of a-SiO:H absorber by alloying with oxygen can affect the FF, we aimed to achieve high photosensitivity by minimizing CO2 gas addition. Improving optical gap(Eopt) has been attained by strong hydrogen dilution combined with lowering substrate temperature down to 100 [°C]. Small amount of the CO2 was added in order to disturb microcrystalline formation by high hydrogen dilution. The developed a-SiO:H has high photosensitivity (~2x105) and high Eopt of 1.85 [eV], which contributed to attain remarkable FF of 74 [%] and high Voc (>1 [V]). As a result, high power conversion efficiency of 7.18 [%] was demonstrated by using very thin absorber layer of only 100 [nm], even though we processed all experiment at extremely low temperature of 100 [°C]. © The Korean Institute of Electrical Engineers.