This study presents a systematic investigation of high-efficiency flexible copper indium gallium selenide(CIGS)thin-film solar cells fabricated using an optimized three-stage co-evaporation process.The research focuse...This study presents a systematic investigation of high-efficiency flexible copper indium gallium selenide(CIGS)thin-film solar cells fabricated using an optimized three-stage co-evaporation process.The research focuses on two key innovations:(1)NaF pre-deposition for controlled alkali metal doping and(2)active regulation of In/Ga evaporation timing during the initial growth stage to precisely engineer the Ga/(Ga+In)(GGI)ratio gradient throughout the absorber layer depth.Through comprehensive characterization of structural properties,elemental distributions,and device performance,we demonstrate that the synergistic combination of Na doping and tailored Ga grading effectively addresses critical challenges in flexible CIGS devices,including back-surface Ga accumulation and non-ideal bandgap profiles.Our results reveal that this dual optimization strategy significantly enhances charge carrier mobility and collection efficiency,ultimately leading to substantial improvements in overall solar cell performance.The findings establish a robust materials engineering approach for developing high-performance flexible photovoltaic devices through precise control of compositional gradients and defect passivation.展开更多
Despite sulfurization offers the advantage of improving the photovoltaic performance in preparing Cu(In,Ga)Se2(CIGS)absorbers,deep level defects in the absorber and poor energy level alignment on the front surface are...Despite sulfurization offers the advantage of improving the photovoltaic performance in preparing Cu(In,Ga)Se2(CIGS)absorbers,deep level defects in the absorber and poor energy level alignment on the front surface are still main obstacles limiting the improvement of power co nversion efficiency(PCE)in sulfided CIGS solar cells.Herein,an in-situ Na doping strategy is proposed,in which the tailing effect of crystal growth is used to promote the sulfurization of CIGS absorbers.It is found that the grain growth is supported by Na incorporating due to the enrichment of NaSe_(x)near the upper surface.The high soluble Na during grain growth can not only suppress intrinsic In_(Cu) donor defects in the absorber,but also tailor S distribution in bulk and the band alignment at the heterojunction,which are both beneficial for the effective electron carriers.Meanwhile,the Na aggregation near the bottom of the absorber also contributes to the crystalline quality increasing and favorable ultra-thin MoSe_(2) formation at back contact,resulting in a reduced barrier height conducive to hole transport.PCE of the champion device is as high as 16.76%with a 28%increase.This research offers new insights into synthesizing CIGS solar cells and other chalcogenide solar cells with superior cell performance when using an intense sulfurization process.展开更多
Solution-processed Cu(In,Ga)Se_(2)(CIGS) solar cells suffer from serious carrier recombination and power conversion efficiency(PCE) loss because of the poor film properties and easy formation of defects.Herein, we pro...Solution-processed Cu(In,Ga)Se_(2)(CIGS) solar cells suffer from serious carrier recombination and power conversion efficiency(PCE) loss because of the poor film properties and easy formation of defects.Herein, we propose Ag&Se co-selenization strategy to enhance the crystallization and passivate harmful defects of the CIGS films. The formation of Ag-Se phase during the selenization process enables the formation of large grains and suppresses the deep level defects. It is found that Ag doping can enlarge the depletion region width, lower the Urbach energy and prolong the carrier lifetime. As a result, a champion solution-processed CIGS solar cell presents a high efficiency of 16.48% with the highly improved opencircuit voltage(VOC) of 662 m V and fill factor(FF) of 75.8%. This work provides an efficient strategy to prepare high quality solution-processed CIGS films for high-performance CIGS solar cells.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2024YFB4205300)the National Natural Science Foundation of China(Grant No.52173243)+2 种基金the Natural Science Foundation of Guangdong Province(Grant No.2021A1515011409)Shenzhen&Hong Kong Joint Research Program(Grant No.SGDX20201103095605015)SIAT-CUHK Joint Laboratory of Photovoltaic Solar Energy.
文摘This study presents a systematic investigation of high-efficiency flexible copper indium gallium selenide(CIGS)thin-film solar cells fabricated using an optimized three-stage co-evaporation process.The research focuses on two key innovations:(1)NaF pre-deposition for controlled alkali metal doping and(2)active regulation of In/Ga evaporation timing during the initial growth stage to precisely engineer the Ga/(Ga+In)(GGI)ratio gradient throughout the absorber layer depth.Through comprehensive characterization of structural properties,elemental distributions,and device performance,we demonstrate that the synergistic combination of Na doping and tailored Ga grading effectively addresses critical challenges in flexible CIGS devices,including back-surface Ga accumulation and non-ideal bandgap profiles.Our results reveal that this dual optimization strategy significantly enhances charge carrier mobility and collection efficiency,ultimately leading to substantial improvements in overall solar cell performance.The findings establish a robust materials engineering approach for developing high-performance flexible photovoltaic devices through precise control of compositional gradients and defect passivation.
基金supported by the National Natural Science Foundation of China(62204074)the Hebei Natural Science Foundation(F2022201061,F2023201025)+2 种基金the Open bidding for selecting the best candidates of Baoding(2023chuang206)the High-level Talent Research Startup Project of Hebei University(521100221085)the Post-graduate's Innovation Fund Project of Hebei University(HBU2024BS030).
文摘Despite sulfurization offers the advantage of improving the photovoltaic performance in preparing Cu(In,Ga)Se2(CIGS)absorbers,deep level defects in the absorber and poor energy level alignment on the front surface are still main obstacles limiting the improvement of power co nversion efficiency(PCE)in sulfided CIGS solar cells.Herein,an in-situ Na doping strategy is proposed,in which the tailing effect of crystal growth is used to promote the sulfurization of CIGS absorbers.It is found that the grain growth is supported by Na incorporating due to the enrichment of NaSe_(x)near the upper surface.The high soluble Na during grain growth can not only suppress intrinsic In_(Cu) donor defects in the absorber,but also tailor S distribution in bulk and the band alignment at the heterojunction,which are both beneficial for the effective electron carriers.Meanwhile,the Na aggregation near the bottom of the absorber also contributes to the crystalline quality increasing and favorable ultra-thin MoSe_(2) formation at back contact,resulting in a reduced barrier height conducive to hole transport.PCE of the champion device is as high as 16.76%with a 28%increase.This research offers new insights into synthesizing CIGS solar cells and other chalcogenide solar cells with superior cell performance when using an intense sulfurization process.
基金National Natural Science Foundation of China (62104061, 62074052, 61974173 and 52072327)。
文摘Solution-processed Cu(In,Ga)Se_(2)(CIGS) solar cells suffer from serious carrier recombination and power conversion efficiency(PCE) loss because of the poor film properties and easy formation of defects.Herein, we propose Ag&Se co-selenization strategy to enhance the crystallization and passivate harmful defects of the CIGS films. The formation of Ag-Se phase during the selenization process enables the formation of large grains and suppresses the deep level defects. It is found that Ag doping can enlarge the depletion region width, lower the Urbach energy and prolong the carrier lifetime. As a result, a champion solution-processed CIGS solar cell presents a high efficiency of 16.48% with the highly improved opencircuit voltage(VOC) of 662 m V and fill factor(FF) of 75.8%. This work provides an efficient strategy to prepare high quality solution-processed CIGS films for high-performance CIGS solar cells.
