Solution-processed n-type fullerene field-effect transistors prepared using CVD-grown graphene electrodes: improving performance with thermal annealing

Abstract

Solution-processed organic field effect transistors (OFETs), which are amenable to facile large-area processing methods, have generated significant interest as key elements for use in all-organic electronic applications aimed at realizing low-cost, lightweight, and flexible devices. The low performance levels of n-type solution-processed bottom-contact OFETs unfortunately continue to pose a barrier to their commercialization. In this study, we introduced a combination of CVD-grown graphene source/drain (S/D) electrodes and fullerene (C60) in a solution-processable n-type semiconductor toward the fabrication of n-type bottom-contact OFETs. The C60 coating in the channel region was achieved by modifying the surface of the oxide gate dielectric layer with a phenyl group-terminated self-assembled monolayer (SAM). The graphene and phenyl group in the SAMs induced π-π interactions with C60, which facilitated the formation of a C60 coating. We also investigated the effects of thermal annealing on the reorganization properties and field-effect performances of the overlaying solution-processed C60 semiconductors. We found that thermal annealing of the C60 layer on the graphene surface improved the crystallinity of the face-centered cubic (fcc) phase structure, which improved the OFET performance and yielded mobilities of 0.055 cm(2) V(-1) s(-1). This approach enables the realization of solution-processed C60-based FETs using CVD-grown graphene S/D electrodes via inexpensive and solution-process techniques.

Wafer‐Scale Growth of Aligned C60 Single Crystals via Solution‐Phase Epitaxy for High‐Performance Transistors

“…In this way, the trap carrier density of the 1D C 60 crystal array is estimated to be as low as 3.31 × 10 −9 C cm −2 , which is 7-136 times lower than that of the C 60 crystals prepared by previously reported methods (Figure 4f and Table S1, Supporting Information). [11][12][13][14]20,[46][47][48][49][50][51][52] The excellent device performance of the OFET device could be attributed to the high crystal quality of 1D C 60 single crystal and the optimized device structure with good electrical contacts. Next, the performance uniformity of 55 C 60 crystal array-based devices on the same substrate was investigated.…”

“…Notably, the maximum mobility is as high as 5.09 cm 2 V −1 s −1 for the C 60 single-crystal array-based OFETs, which is at least 3.5 times higher than that of the OFETs based on the previously reported C 60 polycrystalline films (Table S2, Supporting Information). [20][21][22]46,[49][50][51][52] Finally, the air stability of the C 60 single-crystal array-based OFET was examined. As shown in Figure S14, Supporting Information, the mobility value of the OFET decreased ≈40% after 1-day exposure in air, which is comparable to the air stability of the reported C 60 polycrystalline films.…”

“…[18] Though most of the current applications rely on the use of C 60 thin films, further improvement of the device performance is hindered by the intrinsic problems in the polycrystalline thin-film systems, such as abundant grain boundaries as well as a large number of defects. [19][20][21][22] Compared with the polycrystalline thin films, C 60 single crystals with intrinsic lack of defects and grain boundaries possess superior optoelectronic properties in terms of higher carrier mobility and longer carrier diffusion length. [8] Many efforts have been devoted to growing high-quality C 60 single crystals, [23][24][25] but sizes of the obtained C 60 single crystals are usually very small (from several hundreds of nanometers to a few micrometers), [26] and the C 60 crystals tend to form 0D morphologies owing to the naturally 0D structure of the C 60 molecules.…”

A Quinacridone-Diphenylquinoxaline-Based Copolymer for Organic Field-Effect Transistors

“…The channel resistances ( R total W ) were obtained from the inverse slope of the output curves in the linear regime at V G = −80 V. As shown in Figure 4, the channel resistance value resulting from the as-cast PQCTQx film was measured to be 21.5 MΩcm, and the values resulting from the films annealed at 150 °C and 200 °C were measured to be 16.7 MΩcm and 25.6 MΩcm, respectively. The relatively low channel resistance value resulting from the film heat treated at 150 °C led to the better field-effect mobility in its device [21,22].…”

Studies of suspension droplet evaporation on soft substrates for stretchable electronics applications

“…There are many deposition techniques to fabricate electronic devices. For instance, the deposition via gas-phase methods, such as chemical vapor deposition (CVD) [39,40], physical vapor deposition (PVD) [41], sputtering [42,43], and electro-spinning [44] have been reported. To lower the manufacturing cost, many economic processes are being used, such as drop casting [45], spin coating [46], and additive manufacturing [25,47].…”