A new doping strategy of Spiro-OMeTAD: towards Instantly Efficient and Stable Perovskite Solar Cells
Feng Gao a
a Linköping University, Bredgatan, 33, Norrköping, Sweden
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Invited Speaker, Feng Gao, presentation 141
DOI: https://doi.org/10.29363/nanoge.hopv.2022.141
Publication date: 20th April 2022

Record efficiencies of perovskite solar cells (PSCs) are obtained with spiro-OMeTAD as the hole transport layer. Spiro-OMeTAD is conventionally doped by hygroscopic lithium salts with the assistance of volatile 4-tert-butylpyridine, which, however, brings a time-consuming doping process as well as poor device stability. We successfully develop an instantly efficient and clean doping strategy to replace the conventional spiro-OMeTAD doping. As demonstrated by experimental and theoretical investigations, the radical dopant leads to significant increase of the conductivity through efficient hole polarons generation. The ionic salts can further modulate the work function with negligible effects on the film conductivity, critical for reaching optimal VOC values by a favorable energetic level alignment. Spiro-OMeTAD based on our new doping strategy enables PSCs with a high power conversion efficiency over 25% and an excellent stability against moisture, heat and illumination. Our findings pave the way for achieving PSCs with high efficiencies and excellent stability at the same time. In addition, our doping strategy goes beyond traditional organic semiconductor doping, providing new understanding of organic doping mechanisms which can inspire further optimizations of different optoelectronic devices.

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