Synthesis and Application of Functionalized Diblock Amphiphilic Fullerene Derivatives

Abstract

A series of functionalized amphiphilic diblock fullerene derivatives C60‐4TPB, C60‐2DPE, C60‐4HTPB, C60‐PHFBS, and C60‐2BEFPE are developed and applied as the modification layers on zinc oxide (ZnO) in inverted organic solar cell (OSC) devices. By spin‐coating ZnO, the fullerene derivatives layer can reduce the work function of ZnO via modulation of the interfacial dipoles. When introducing solvent treatment by toluene during the preparation of films, the order of the fullerene derivatives layer are clearly increased, which are supported by X‐ray diffraction and contact angle of water measurements. The OSCs devices modified with those fullerene derivatives show power conversion efficiency of 8.62%, 9.21%, 8.86%, 9.14%, and 9.15% based on poly‐[4,8‐bis(5‐(2‐ethylhexyl)‐thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]‐dithiophene‐alt‐3‐fluoro thieno‐[3,4‐b] thiophene‐2‐carboxylate] (PTB7‐Th) and [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM) blend, respectively. All the results indicate that the development of diblock amphiphilic fullerene derivatives opens a new opportunity to modify the present defects of ZnO by simultaneously modulating interfacial work functions, the wetting properties of the interlayer, and the active layer.

Materials for Interfaces in Organic Solar Cells and Photodetectors

“…With the continuous development of nanotechnology, the application of nanomaterials and 2D materials will become extensively wider, especially fullerene materials, which can be used not only as acceptor materials but also as interfacial materials by introducing different side chains. For example, the charges’ extraction and transport are increased by the addition of an n-type (or p-type) doping group; the defects could be induced and carrier recombination could be prevented by introducing the hydrophilic side chain . In addition, we can ascertain that there are much less AIL materials than CIL materials from this review, and the commonly used AILs are only PEDOT:PSS and MoO 3 .…”

“…In addition, the studies have shown that these materials could passivate the defects of the ZnO interlayer, hence fabricating a hybrid ETL with better quality. Liu et al incorporated C 60 -4TPB, C 60 -2DPE, C 60 -4HTPB, C 60 -PHFBS, and C 60 -2BEFPE between ZnO and the active layer, achieving the PCE of 8.62%, 9.21%, 8.86%, 9.14%, and 9.15%, respectively . Additionally Kumar et al obtained a 60% enhancement concerning PCE by depositing C 70 on ZnO film …”

“…For example, the charges' extraction and transport are increased by the addition of an ntype (or p-type) doping group; 182 the defects could be induced and carrier recombination could be prevented by introducing the hydrophilic side chain. 183 In addition, we can ascertain that there are much less AIL materials than CIL materials from this review, and the commonly used AILs are only PEDOT:PSS and MoO 3 . Thus, finding other anode-modified materials with wide applicability and low-cost has great significance for the development of optoelectronic devices.…”

Fullerene‐Based Interlayers for Breaking Energy Barriers in Organic Solar Cells

“…Some of the fullerene derivatives showed a self‐assembly on the ZnO X layer, which improved the contact between ZnO X and active layer. Finally, these fullerene derivatives can passivate the ZnO X surface, optimize ZnO X WF , and suppress charge recombination losses in solar cell devices, improving V OC and J SC …”

Functionalized Amphiphilic Diblock Fullerene Derivatives as a Cathode Buffer Layer for Efficient Inverted Organic Solar Cells

“…Based on the characteristic of low work function, zinc oxide (ZnO) was always used as a buffer layer to decrease the barrier of the cathode electrode with an ohmic contact in inverted OSCs. − However, the trap sites and defects of ZnO always required an amphiphilic interface material to be introduced between ZnO and the active layer to get an efficient device. − The most commonly used interface material to modify ZnO was the amphiphilic organic material, especially the functionalized amphiphilic fullerene derivatives. − Amphiphilic fullerene derivatives functionalized with polar groups can be regarded as hydrophobic–hydrophilic diblock molecular, in which fullerene and polar groups were the hydrophobic and hydrophilic blocks, respectively. − The introduced amphiphilic diblock fullerene derivative layer can also guarantee the improvement of interface compatibility when introducing to modify ZnO in OSC devices. − …”