Evaluation of P3HT:PC61BM with different lateral sizes and contents of graphene oxide (GO) or reduced graphene oxide (rGO) in small and large area solar cells Lucas Tienne 1,2,3 , Maria de Fátima Vieira Marques 1 , Armin Wedel 2 , Jiyong Kim 2 , Fabian Loepthien 2 , Yohan Kim 2 , Ana Flávia Nogueira 3 1 Universidade Federal do Rio de Janeiro (IMA-UFRJ), Brazil. 2 Fraunhofer Institute for Applied Polymer Research (IAP-Fraunhofer), Germany. 3 Universidade Estadual de Campinas (IQ-UNICAMP), Brazil. The photovoltaic sector even stands out in relation to other renewable energy sources due to a theoretical capacity to supply the planet with about 10,000 times more energy than the global daily consumption[1]. However, the materials currently applied in this industry have limitations in terms of processing, flexibility, weight, size, which restricts its accessibility to society due to the cost involved. Thus, polymer solar cells can overcome most of these problems. Such keywords also strongly allude to the uses of graphene, which is a nanomaterial that presents an excellent set of properties, such as high electrical conductivity, transparency, flexibility, and mechanical residence. Its application in photovoltaic devices still limited not only because it is difficult to obtain, but also because there is no standardization and quality control of the materials produced[2]. This makes the comparison of results between those surveyed around the world compromised and the understanding of the impact of this nanomaterial on photovoltaic devices masked. Thus, the present work used the combination of the world reference semiconductor homopolymer poly(3-hexylthiophene)(P3HT) with PC61BM (1:1) and evaluated the insertion of graphene oxide (GO) and reduced graphene oxide (rGO) in different proportions (0.5%; 1.0%; 2.5% and 5.0%) synthesized by the improved Hummers method. In addition, two types of graphite were used to generated GO and rGO with different lateral size distribution. The photovoltaic devices were prepared using ternary composites as active layer with pixels considered of small area and large area to verify its scaling up. The photovoltaic parameters of the devices were characterized by JxV curves and its morphology by Optical Microscopy (OM). The GO, although it has lower electrical conductivity than rGO, improved the power conversion efficiency (PCE) from 2.58±0.32% to 2.81±0.10% for the small pixels mainly because it has oxygenated groups that add better affinity with P3HT, reducing exciton recombination. Devices with rGO obtained a reduction in efficiency to 2.36±0.15%, mainly due to the reduction of the fill factor. Both GO and rGO favor a higher Jsc due to the light trapping phenomenon. Regarding the large area devices, the control device and the one containing rGO with smaller lateral size showed similar efficiencies, 1.98±0.22% and 1.94±0.16%, respectively. The devices with GO had an improvement of around 13% in efficiency. The graphenes obtained with larger lateral size significantly reduced the efficiency of the device. By the OM it was observed that the particles end up penetrating beyond the metallic contact, which should generate a leakage of the current and interfaces that potentiate the recombination processes. Preliminary studies also suggest that the insertion of graphene tends to add better stability. References 1. TIENNE, L.G.P.; PAULA, T.P.; MARQUES, MF.V. Mater Sci Eng B (2023), DOI: 10.1016/j.mseb.2023.116505 2. RÜHLE, S.; SHALOM, M.; ZABAN, A. Chemphyschem (2010),DOI: 10.1002/cphc.201000069
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