Sustainable Recycling of Selenium‐Based Optoelectronic Devices

Abstract

Selenium (Se), the world's oldest optoelectronic material, has been widely applied in various optoelectronic devices such as commercial X‐ray flat‐panel detectors and photovoltaics. However, despite the rare and widely‐dispersed nature of Se element, a sustainable recycling of Se and other valuable materials from spent Se‐based devices has not been developed so far. Here a sustainable strategy is reported that makes use of the significantly higher vapor pressure of volatile Se compared to other functional layers to recycle all of them from end‐of‐life Se‐based devices through a closed‐space evaporation process, utilizing Se photovoltaic devices as a case study. This strategy results in high recycling yields of ≈ 98% for Se and 100% for other functional materials including valuable gold electrodes and glass/FTO/TiO2 substrates. The refabricated photovoltaic devices based on these recycled materials achieve an efficiency of 12.33% under 1000‐lux indoor illumination, comparable to devices fabricated using commercially sourced materials and surpassing the current indoor photovoltaic industry standard of amorphous silicon cells.

Increasing the Collection Efficiency in Selenium Thin-Film Solar Cells Using a Closed-Space Annealing Strategy

“…Selenium thin films are predominantly synthesized by evaporating an amorphous layer of selenium, followed by a thermal annealing process to crystallize the as-deposited film. − However, the temperature window leading to the highest power conversion efficiencies (PCE) is fairly narrow, , and the high vapor pressure of selenium poses challenges in growing high-quality crystalline selenium thin films without compromising the surface morphology and forming pinholes. − …”