Graphene quantum dots (GQDs), a newly emerging 0-dimensional graphene based material, have been widely exploited in optoelectronic devices due to their tunable optical and electronic properties depending on their functional groups. Moreover, the dispersibility of GQDs in common solvents depending on hydrophobicity or hydrophilicity can be controlled by chemical functionalization, which is particularly important for homogeneous incorporation into various polymer layers. Here we report that a surface-engineered GQD-incorporated polymer photovoltaic device shows enhanced power conversion efficiency (PCE), where the oxygen-related functionalization of GQDs enabled good dispersity in a PEDOT:PSS hole extraction layer, leading to significantly improved short circuit current density (Jsc) value. To maximize the PCE of the device, hydrophobic GQDs that are hydrothermally reduced (rGQD) were additionally incorporated in a bulk-heterojunction layer, which is found to promote a synergistic effect with the GQD-incorporated hole extraction layer.
Bibliographical noteFunding Information:
This research was supported by the Basic Science Research Program (NRF-2013R1A2A1A09014038, 2011-0030254, 2011-00006286, 2014M3A7B4051747, 2011-0017587), the Global Ph.D fellowship program (NRF-2012H1A2A1016034), the Global Research Lab (GRL) Program (2011-0021972), and the Global Frontier Research Program (2011-0031629) through the National Research Foundation of Korea (NRF) funded by the Korean government (MEST and MKE). B. H. H. appreciates the financial support from the SBS foundation. Institutional Program. S. Bae appreciates the financial support from the Korea Institute of Science and Technology (KIST) Institutional Program (2Z04420) and the Graphene Materials/Components Development Project (10044366) through the Ministry of Trade, Industry, and Energy (MOTIE), Republic of Korea.
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