Simultaneous reduction and sulfonation of graphene oxide for efficient hole selectivity in polymer solar cells

• Published in: Current applied physics 2018, 18(5), , pp.599-610
• Main Authors: Ali, Asghar, Khan, Zuhair S., Jamil, Mahmood, Khan, Yaqoob, Ahmad, Nisar, Ahmed, S.
• Format: Article
• Language: English
• Subjects: Graphene; Hole extraction layer; P3HT:PC61BM solar cell; Reduction; Sulfonation; 물리학
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2018.02.016

We developed sulfonated, reduced graphene oxide (S-RGO) through fuming/concentrated sulfuric acid treatment of graphene oxide (GO) in ambient conditions. It was demonstrated that the optical band gap and electrical conductivity of S-RGO are easily tunable, and depend on the level of reduction and sulfonation of GO. Whereas, reduction and sulfonation were found dependent on SO3 content, acid strength, and gas tightness of the reaction mixture. It's actually the water content of oleum that determines the nature of the final product. The easily adjustable band gap and electrical conductivity suggest that S-RGO can be employed as a potential hole extraction layer (HEL) material for several donor-acceptor systems. For P3HT:PC61BM based inverted polymer solar cells, it was observed that the shape of the J–V curve is tailorable with the choice of HEL. Compared to a 2.75% power conversion efficiency (PCE) attained with PEDOT:PSS, a PCE of 2.80% was achieved with tuned S-RGO. Our results imply that an S-RGO of sufficiently high band gap and conductivity can replace some of the state of the art HEL materials for a host of device applications. [Display omitted] •Development of S-RGO through acid treatment of GO in ambient.•Tuning S-RGO properties via control of water content of the reaction mixture.•Employing the S-RGOs as hole extraction layer materials in P3HT:PC61BM solar cells.•Performance interpretation in terms of series & shunt resistances (RS & RSh).•RS & RSh elaboration in terms of energy level diagram and the nature of the S-RGO.