Stoichiometrically-Adjusted Cobalt Sulfide Nanocrystals Enhanced Hole Extraction Ability of Undoped Spiro-OMeTAD HTLs for Highly Efficient and Stable Perovskite Solar Cells
Seoyeong Lee a, Subin Yu a, Jae Yeon Kim a, Min Jae Ko a
a Department of Chemical Engineering, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu,, Ansan, 426, Korea, Republic of
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP24)
Tokyo, Japan, 2024 January 21st - 23rd
Organizers: Qing Shen and James Ryan
Poster, Seoyeong Lee, 105
Publication date: 18th October 2023

Perovskite solar cells (PSCs) have emerged as promising next-generation photovoltaic devices because of their superior optical and electronic properties. In recent years, organic hole transporting material (HTM) based PSCs have been reported with remarkable increase in the photovoltaic performance. As power conversion efficiency (PCE) of PSCs employing organic HTM has dramatically increased, expectations toward commercialization of PSCs are increasing. However, traditional organic HTMs have a couple of issues such as cost and stability. In the view of this limitation, we have developed the new p-type inorganic HTM. Cobalt sulfide compounds are one of the promising materials to replace conventional organic HTMs, which are less expensive and earth-abundant. Nevertheless, synthesis of cobalt sulfide is tricky to control the stoichiometric ratio. Here, we synthesized novel inorganic HTMs as a stoichiometrically adjusted p-type cobalt sulfide nanocrystals (CoxSy NCs). Cobalt sulfide nanocrystals synthesized in this study display the excellent hole transport ability owing to its high conductivity and suitable energy levels for hole extraction for PSCs. CoxSy NCs HTLs-based PSCs exhibited power conversion efficiency (PCE) nearly comparable to dopants-free spiro-OMeTAD HTM-based PSCs. Especially, the PSCs with mixed CoxSy NCs (with undoped Spiro-OMeTAD) HTLs exhibited PCE of 20.48 % which belongs to the high-performance, considering ionic additive-free HTMs. Furthermore, the PCSs employing cobalt sulfide showed an initial efficiency of 92 % even after exposure to 70 % relative humidity for 1000 hours. These new p-type CoxSy NCs would support environmentally and economically sustainable development of PSC and diverse optoelectronic area.

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