Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
DOI: https://doi.org/10.29363/nanoge.hopv.2020.086
Publication date: 6th February 2020
Organometallic halide perovskites are promising materials for photovoltaic applications, with achieved efficiencies over 23% at lab-scale. For promoting the use of perovskite solar cells (PSCs) in practical applications, it is essential to achieve an upscaling route, which ensures environmentally friendly processing of stable and highly efficient PSCs. In this presentation, we demonstrate and discuss the feasibility of upscaled production of PSCs via roll-to-roll (R2R) slot-die (SD) coating route. One of the main parts of the presentation involves how we have achieved these results with solvent selection & optimization. Most of the solvents used to prepare the inks for charges transport and absorber layers are toxic, carcinogenic, or harmful to environment. Being an ambient-exposed coating technique, most of the solvents for preparing the inks for layers has to be replaced by safer alternatives. Apart from that, as a result of high roll speeds, fast crystallization kinetics have to be investigated and implemented (preferably under ambient conditions) in order to obtain a uniform coating with desired morphology. We have performed R2R SD coating runs of electron transport layers and perovskite absorber layers on flexible substrates with a width of 30 cm and a web speed of 3-5 m/min, and developed layer drying methods for R2R coating. The stacks were completed by coating the hole transport layer using sheet-to-sheet (S2S) SD processing. The average stabilized power conversion efficiencies obtained from this n-i-p configurated stack reached to an average value of 12% (measured over different areas) and with the best value of 13.5%. This demonstrated value is an achievement towards future commercialization of large scale processing of PSCs. In addition, we currently investigate the R2R coating of perovskite layers on R2R-coated hole transport layers in order to realize p-i-n configuration. At this stage, this investigation focuses on the realization of uniform and pinholes-free coatings of perovskite and hole transport layers. Finally, we briefly demonstrate our initial results on flexible perovskite tandem solar cells realized by spin coating, yielding an efficiency of 21.5%, and we discuss the potential of scalability of this lab-scale cell.