Kang, Gil-Seong Lee, Sungho Yeo, Jun-Seok Choi, Eun-Su Lee, Doh C. Na, Seok-In Joh, Han-Ik 2024-01-19T19:04:22Z 2024-01-19T19:04:22Z 2021-09-05 2019-09-15 1385-8947 https://pubs.kist.re.kr/handle/201004/119569 Graphene quantum dots (GQDs) are promising materials for optoelectronic devices because their band-gap, derived from quantum confinement and edge effects, can be easily tuned via their size or surface/edge states. In this paper, a novel approach to synthesize nitrogen-and oxygen-doped GQDs (NO-GQDs) is presented. Nitrogen and oxygen are mainly bound at the GQD edges, resulting in high crystallinity and good electrical properties. A simple solvothermal reaction using N-methyl-2-pyrrolidone (NMP), whose surface energy is similar to that of graphite as a raw material, can simultaneously exfoliate, cut, and finally transform the graphite into the GQDs with heteroatoms derived from the decomposed NMP solution. The synthesized NO-GQDs have a less defective and more selectively edge-functionalized structure compared to other reported GQDs. The electrical properties of NO-GQDs are investigated using them as the additive of hole-transporting materials (HTMs) in an optoelectronic device such as perovskite solar cells (PeSCs). Compared with PEDOT:PSS, a mixture of NO-GQDs and PEDOT:PSS shows a 36.2% increase in the power conversion efficiency (PCE) (maximum PCE: 11.47%) and good device stability. Therefore, it is believed that the improvement of photovoltaics is solely attributed from NO-GQDs which act as a positive role of faster hole transfer. We could confirm that the NO-GQDs facilitate hole-extraction from a photoactive layer and guarantee the more stable operation of PeSCs. English ELSEVIER SCIENCE SA LARGE-SCALE PREPARATION PEROVSKITE SOLAR-CELLS TUNABLE PHOTOLUMINESCENCE CARRIER SEPARATION OXIDE EFFICIENT PERFORMANCE SIZE GRAPHITE WATER Graphene quantum dots with nitrogen and oxygen derived from simultaneous reaction of solvent as exfoliant and dopant Article 10.1016/j.cej.2019.04.192 1 CHEMICAL ENGINEERING JOURNAL, v.372, pp.624 - 630 CHEMICAL ENGINEERING JOURNAL 372 624 630 scie scopus 000471670400059 2-s2.0-85064863269 Engineering, Environmental Engineering, Chemical Engineering Article LARGE-SCALE PREPARATION PEROVSKITE SOLAR-CELLS TUNABLE PHOTOLUMINESCENCE CARRIER SEPARATION OXIDE EFFICIENT PERFORMANCE SIZE GRAPHITE WATER Graphene Nitrogen and oxygen doped graphene quantum dots (NO-GQDs) Solvothermal reaction Graphite exfoliation Perovskite solar cells Hole-transporting materials (HTMs)