Direct Formation of Thin Single Crystals of Organic Semiconductors onto a Substrate

Abstract

We have developed a novel and convenient method of crystal growth in a liquid phase. This method produces directly onto a substrate well-defined polygon organic thin crystals with uniform thickness. The thin crystals are found to be single crystals of high quality. We show various illustrations including thiophene/phenylene co-oligomers and an oligophenylene. The organic crystal transistors based on these crystals showed good device performance. These thin single crystals are expected to be suitably applied to electronic devices.

Refractive Index Dispersion and Anisotropic Group Refractive Indices of Rubrene Crystals

“…We observed the size and shape of the crystals using a NIKON ECLIPSE LV100POL polarizing microscope with an EXFO X-Cite 120 mercury lamp (white light: 294.5 to 812.5 nm) [13]. Thickness measurements and X-ray diffraction (XRD) measurements were performed in the manner same as before [17].…”

Organic semiconductors for device applications: current trends and future prospects

“…This scheme was equally applicable in the case of a large variety of materials, including rubrene, pentacene, tetracene, C 60 , F 16 CuPc, and TCNQ. It was noted that material sublimation and crystal growth took only 5 min to complete in the case of pentacene; in contrast, it took 2 h for growing C 60 film [323]. In this experiment, the nucleation was specifically confined to OTS-stamped regions, leaving the rest of the SiO 2 background unaffected.…”

“…Despite having synthesized a number of semiconducting organic crystals so far [309], only a few of them were successfully processed into samples fit for transport measurements and still fewer were available into few micronsized freestanding single crystals [320][321][322][323][324][325][326][327]. This clearly explains why there is a need for going into thin-film-based device development and not on large-sized wafers as in the case of Si and other inorganic semiconductors.…”

“…On the contrary, unwanted deposition of smaller-sized debris during solution and/or solvent-based processing is equally troublesome. In order to mitigate these problems, a number of alternative schemes were developed including fabrication of free-standing single-crystal devices [18,352], electrostatic bonding of a single crystal onto prefabricated device electrodes [19,302,323,353], formation of single crystals by drop-casting from organic solutions [320,354], and solvent-grown organic single-crystal nanowires [355] as reported in the published literature. Keeping various types of the associated problems in view, several alternate strategies were developed to deposit organic single crystals directly onto the substrate: either using PVT or solution-based processing techniques [224].…”

“…In 2006, patterned growth of large-area organic single crystal was successfully attempted for OFET applications [323], where octadecyltriethoxysilane (OTS) film was microcontact printed onto a clean SiO 2 /Si substrate using a polydimethylsiloxane (PDMS) stamp prior to deposition [274]. This scheme was equally applicable in the case of a large variety of materials, including rubrene, pentacene, tetracene, C 60 , F 16 CuPc, and TCNQ.…”