Thermal Radiation Annealing for Overcoming Processing Temperature Limitation of Flexible Perovskite Solar Cells.

Common polymeric conductive electrodes, such as polyethylene terephthalate (PET) coated with indium tin oxide, face a major challenge of their low processing-temperature limits, attributed to PET's low glass transition temperature (Tg of 70-80 °C). This limitation significantly narrows the scope of material selection, limits the processing techniques applicable to the low Tg, and hinders the ripened technology transfer from glass substrates to them. Addressing the temperature constraints of the flexible substrates is impactful yet underexplored, with broader implications for fields beyond photovoltaics. Here we introduce a new thermal radiation annealing methodology to address this issue. By applying above Tg radiation annealing in conjunction with thermoelectric cooling, we successfully create highly ordered molecular packing on PET substrates, which are exclusively unachievable due to PET's low thermal tolerance. As a result, in the context of perovskite solar cells, this approach enables the circumvention of high-temperature annealing limitations of PET substrates, leading to a remarkable flexible device efficiency of 22.61% and a record fill factor of 83.42%. This approach proves especially advantageous for advancing the field of flexible optoelectronic devices. This article is protected by copyright. All rights reserved.