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Separation and recovery of materials from the waste light emitting diode (LED) modules by solvent method
摘要： Nowadays, a large quantity of Light Emitting Diodes (LEDs) have been produced and updated with the development of optoelectronic industry. At the same time, many waste LEDs are discarded. However, there are many metals and non-metals in waste LEDs, which may cause secondary pollution and waste of resources if disposed improperly. In this study, solvent method was used to dissociate the waste LED modules and recycle resources. Firstly, the components of the waste LED modules were analyzed. The main component of the transparent plastic part, usually used as packaging materials, is cured epoxy resin, and the main component of the white plastic part as the skeleton of LED modules is a mixture of polyphenylene oxide (PPO) and polystyrene (PS). Then, eight organic solvents, [EMIM+]BF4? ion liquid and sodium hydroxide (NaOH) inorganic reagent were tried to separate a 40 × 40 mm2 waste LED module respectively. The results showed that only three organic solvents—dimethylformamide (DMF), dimethylacetamide (DMA), dimethyl-sulfoxide (DMSO) could dissociate the waste LED module very well. The used DMF solution was purified by rotary evaporation, and the regenerative DMF solution could be reused because its property has not changed. The solid residue obtained after rotary evaporating DMF was identified as polystyrene (PS). It was inferred that the waste LED module was dissociated through the DMF dissolving the PS of white plastic. In addition, the effect of DMF, DMA and DMSO dissociating the waste LED modules with the change of temperature was discussed. It was found that the choice of suitable solvent is a key for this method, and the heating temperature was also a very important factor. Finally, it was measured that the cured epoxy resin and the white plastic of the waste LED module accounted for about 31.4% (w/w) and 37.7% (w/w) respectively, which can be recycled. In short, the method not only separated completely the waste LED module and its each part was recycled easily, but the solvents can be reused. This study suggests a new route to recycle LEDs due to its environmentally friendly process, which may exert a significantly beneficial impact on our environment.
关键词： Organic solvent,DMF,LED module
更新于2025-09-23 15:19:57
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Highly Efficient Copper-Rich Chalcopyrite Solar Cells from DMF Molecular Solution
摘要： Theoretical calculation suggests Cu-rich chalcopyrite absorbers contain less defects and have potential to achieve better performance than Cu-poor absorbers. However, this has not been demonstrated due to the detrimental Cu2-xSe impurity remaining in the absorber. Here, we report highly efficient Cu-rich chalcopyrite solar cells by selenizing dimethylformamide molecular precursor solution processed precursor films under high Ar pressure. Characterizations using XRD, Raman, SEM, TEM, c-AFM, PL, and glow discharge optical emission spectroscopy (GDOES) show high pressure selenization enables high quality Cu-rich chalcopyrite absorber materials with stoichiometric composition, smooth surface, high conductivity, and Cu2-xSe free grain boundaries, leading to efficient CuIn(S,Se)2 and Cu(In,Ga)(S,Se)2 devices with power conversion efficiency of 14.5% and 15.2%, both are the best performing chalcopyrite solar cells from non-hydrazine solutions. Our results demonstrate high Ar pressure selenization is a new strategy to fabricate high quality Cu-rich absorber which has great potential to further improve chalcopyrite solar cell efficiency.
关键词： Cu-rich,chalcopyrite,selenization,CIGS,DMF,high pressure
更新于2025-09-12 10:27:22