Turkish Journal of Electromechanics and Energy, cilt.5, sa.2, ss.74-82, 2020 (Diğer Kurumların Hakemli Dergileri)
Solar cell efficiency and durability are some of the critical research areas in the field of solar photovoltaic (PV) technology. Thin-film PV cells have been increasingly used in many industries and applications such as wearable electronics, self-energizing systems, on the roof of electrical vehicles, trains, solar boats, etc. Various types of thin-film solar cells have been investigated, produced, and exploited around the world. Different types of chalcopyrite semiconductors are used in high-efficiency thin-film solar cells, specifically in flexible PV cells. Cu(In,Ga)Se2 (CIGS) solar cells are promising technology among the thin-film solar cells due to their unique features. However, there are many challenges towards the development of the photovoltaic performance of thin-films and ultra-thin-film solar cells. The thickness and surface roughness of the thin-film layer which has a significant effect on the performance of cells, electron recombination, interface contact between thin-film layers, grain size, and grain boundaries can be mentioned as major problems. Many solutions for the cited problems have been investigated and reported. Alkali post-deposition treatment, for example, was noted to reduce the thickness of the absorber. Reduction in absorber thickness leads to a significant decrease in electron recombination which improves the PV performance of CIGS solar cells. Cs post-deposition treatment (Cs-PDT), on the other hand, improves cell performance by creating conduction band upward and valence band downshifts. Low thickness of absorber increase crystallinity and surface roughness of the CIGS absorber. A high amount of Ga concentration is reported to reduce the grain size and major loss of charge carrier. In addition to the high Ga amount, sulfurization is also responsible for decreasing the grain size and the fill factor (FF) of the PV cell.