Noncovalent Functionalization of Graphene Attaching [6,6]-Phenyl-C61-butyric Acid Methyl Ester (PCBM) and Application as Electron Extraction Layer of Polymer Solar Cells

Abstract

A new graphene-fullerene composite (rGO-pyrene-PCBM), in which [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was attached onto reduced graphene oxide (rGO) via the noncovalent functionalization approach, was reported. The pyrene-PCBM moiety was synthesized via a facile esterification reaction, and pyrene was used as an anchoring bridge to link rGO and PCBM components. FTIR, UV-vis, and XPS spectroscopic characterizations were carried out to confirm the hybrid structure of rGO-pyrene-PCBM, and the composite formation is found to improve greatly the dispersity of rGO in DMF. The geometric configuration of rGO-pyrene-PCBM was studied by Raman, SEM, and AFM analyses, suggesting that the C60 moiety is far from the graphene sheet and is bridged with the graphene sheet via the pyrene anchor. Finally rGO-pyrene-PCBM was successfully applied as electron extraction layer for P3HT:PCBM bulk heterojunction polymer solar cell (BHJ-PSC) devices, affording a PCE of 3.89%, which is enhanced by ca. 15% compared to that of the reference device without electron extraction layer (3.39%). Contrarily, the comparative devices incorporating the rGO or pyrene-PCBM component as electron extraction layer showed dramatically decreased PCE, indicating the importance of composite formation between rGO and pyrene-PCBM components for its electron extraction property.

Synthesis and characterization of D-A-A type regular terpolymers with narrowed band-gap and their application in high performance polymer solar cells

“…Among various donor units in the D-A copolymers, pyrene is a completely planar electron-rich moiety, and has prominent optical and electronic properties such as high quantum yield, good thermal stability and strong propensity to form p stack aggregation. 19,20 Some conjugated polymers [21][22][23][24] or small molecules 25,26 containing pyrene moieties have been prepared and showed excellent performance in organic electronics. For example, Hwang and coworkers reported that the incorporation of the pyrene units to the donor-acceptor (D-A) conjugated polymer backbone would improve the hole mobility and decrease the highest occupied molecular orbital (HOMO) energy level of the copolymer, which resulted in a highest PCE of 5.04% obtained.…”

Graphene Derivatives: Controlled Properties, Nanocomposites, and Energy Harvesting Applications

“…This kind of functionalization is preferred Graphene Materials -Structure, Properties and Modificationsfor applications in which optical or electronic properties are critical. A disadvantage is the difficulty of removing the dispersant agent from the graphene surface due to high stability between them [18,19]. Covalent functionalization is based on direct chemical reactions over functional groups of graphene oxide.…”

“…Moreover, it has been reported that incorporation of reduced and functionalized graphene oxide has successfully been carried out as an electron transport layer (ETL), between the active layer and the cathode, improving PCE by 15% for a device with a typical active layer of P3HT: PCBM [18,27].…”

A critical review of nanohybrids: synthesis, applications and environmental implications

“…[47] Similar synthesis processes as well as the water-assisted electric arc process can create an exotic multi-layered hybrid fullerene structure named a 'carbon nano-onion'. [48][49][50] In contrast, the exohedral conjugation of CNTs, graphene and fullerenes employ long-range electrostatic or short-ranged specific interactions [51] ; where conjugating molecules or polymers and covalent functionalities [52] drive the ensemble process. Such functionalisations include: oxidation of CNTs and graphene to attach polar carboxyl or hydroxyl surface groups (-COOH or -OH) [51,53] and attachment of chemically active molecules [54] or polymeric assemblies.…”

“…[48][49][50] In contrast, the exohedral conjugation of CNTs, graphene and fullerenes employ long-range electrostatic or short-ranged specific interactions [51] ; where conjugating molecules or polymers and covalent functionalities [52] drive the ensemble process. Such functionalisations include: oxidation of CNTs and graphene to attach polar carboxyl or hydroxyl surface groups (-COOH or -OH) [51,53] and attachment of chemically active molecules [54] or polymeric assemblies. [55] For example, fullerenes functionalised with porphyrin-derivatives are refluxed with acid-treated CNT-COOH suspensions to generate fullerene-CNT NHs by reaction between the carboxyl functionality on the CNT and aminegroups on the porphyrin molecules.…”