Single crystals of organic semiconductors, being free of grain boundaries and molecular disorders, have been shown to exhibit high performance such as the superior charge carrier mobility and long exciton diffusion. On this point, organic single crystals would be ideal candidate for high performance electronic devices and for intrinsic property studies.
Fullerene materials are among the most widely-used materials for organic electronics. For instance, organic field-effect transistors (OFETs) based on C60 single crystals exhibit electron mobilities exceeding 10 cm2 V−1 s−1, one of the highest among n-channel OFETs. For organic photovoltaics (OPVs), the fullerene derivative of [6,6]-phenyl C61 butyric acid methyl ester (PCBM) is the most widely used electron acceptor and has important functions in OPVs with high power conversion efficiency.
However, most of these organic electronic devices are yet based on fullerene in amorphous phase, which limits the enhancement of the device performance. Grain boundaries and molecular disorder in amorphous thin films scatter the charge carriers by the effect of coulomb scattering, which results in the reduction of charge carrier mobility. Thus, this challenge remains a major bottleneck in the advancement of device performance. In this presentation, I will talk about our research progress on the application of fullerene single crystals in organic electronics. This talk will discuss not only the performance enhancement of OFETs, OPVs, organic photodetectors and perovskite solar cells via crystal engineering, but also the fundamental studies concerning charge transport, excitonic and photovoltaic properties of the nitrogen atom encapsulated fullerene (N@C60) single crystals, PCBM single crystals and single-crystalline p-n heterojunctions.
1. X. Zhao, T. J. S. Dennis,* et al., Antisolvent-assisted controllable growth of fullerene single crystal microwires for organic field effect transistors and photodetectors. Manuscript Submiited.
2. X. Zhao, T. J. S. Dennis,* et al., Understanding charge transport in endohedral fullerene single crystals. Manuscript Submiited.
3. X. Zhao, T. J. S. Dennis,* et al., PCBM single crystals: remarkably enhanced band-like charge transport, broadband UV-Visible-NIR photo-responsivity and improved long-term air-stability. Manuscript Submiited.
4. X. Zhao, S. Wang,* I. D. W. Samuel,* T. J. S. Dennis,* et al., Organic single-crystalline p-n heterojunction as a model to study the intrinsic photovoltaic behaviors: exciton diffusion and charge transport. Manuscript Submiited.
5. X. Zhao, T. J. S. Dennis,* et al., Vertical grown fullerene single crystals for organic photovoltaics. Manuscript in Preparation.
6. X. Zhao, T. J. S. Dennis,* et al., Crystal engineering of charge transporting materials for perovskite solar cells. Manuscript in Preparation.