Selective Crystallization of Organic Semiconductors for High Performance Organic Field-Effect Transistors
ABSTRACT The patterning of an organic layer, a big challenge for organic field-effect transistors (OFETs), have recently received considerable attention. By using copper tetracyanoquinodimethane (Cu-TCNQ) modified copper electrodes with nanostructure, selective polycrystalline growth of organic semiconductors is achieved. For different organic semiconductors, varied ways for crystal growth are observed. The OFETs based on selectively deposited tetracyanoquinodimethane (TCNQ), rubrene, and copper phthalocyanine crystals are fabricated and exhibit good device performance. Rubrene devices exhibit maximum field-effect mobility up to 4.6 cm(2)/(V.s) which is comparable to that of corresponding single crystal device. In addition, an organic inverter made of patterned rubrene and TCNQ exhibits a gain of 23. These results offer a general approach to the fabrication of high performance OFETs and organic circuits.
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ABSTRACT: ABSTRACT: Tuning the electronic band structures such as band-edge position and bandgap of organic semiconductors is crucial to maximize the performance of organic photovoltaic devices. We present a simple yet effective electron irradiation approach to tune the band structure of [6, 6]-phenyl-C61-butyric acid methyl ester (PCBM) that is the most widely used organic acceptor material. We have found that the lowest unoccupied molecular orbital (LUMO) level of PCBM up-shifts toward the vacuum energy level, while the highest occupied molecular orbital (HOMO) level down-shifts when PCBM is electron-irradiated. The shift of the HOMO and the LUMO levels increases as the irradiated electron fluence increases. Accordingly, the band-edge position and the bandgap of PCBM can be controlled by adjusting the electron fluence. Characterization of electron-irradiated PCBM reveals that the variation of the band structure is attributed to the molecular structural change of PCBM by electron irradiation.Nanoscale Research Letters 01/2011; 6:545. · 2.52 Impact Factor