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▼ [21a-PA2-3] Fabrication of crystalline films of 5,5”-bis(4-biphenylyl)-2,2’:5’2”-terthiophene by vaporized film deposition
Keywords:BP3T, polycrystalline material
Thiophene/phenylene co-oligomer, especially 5,5”-bis(4-biphenylyl)-2,2’:5’2”-terthiophene (BP3T) is one of the most interesting and well recognized light-emitting organic semiconductor and effective gain media for organic laser [1]. Recently, electrically pumped gain-narrowed emission has been reported under ambipolar operation of an organic light-emitting transistor (OLET) with single crystal BP3T [2]. However, it is not easy to handle the OLET fabrication procedure with the single-crystal material under controlled size and thickness. Here, we report an alternative OLET fabrication process by using the vaporized film deposition (VFD) [3], which enable us to construct polycrystalline OLET without breaking the vacuum.
[Experiment] In the VFD method, BP3T was first physically vapor-deposited onto a glass substrate. Then, the BP3T/glass sample was placed on the heater, faced up against a SiO2/Si surface, which is spin-coated with fluoropolymer (CYTOP) as a buffer layer. The BP3T/glass was heated at 300°C under a vacuum, then BP3T was transferred onto the SiO2/Si surface.
[Result & Discussion] An atomic force microscopy (AFM) image indicates that the BP3T film transferred onto the SiO2/Si surface and form a layer of the polycrystalline structure while the source film of BP3T on glass is composed of randomly pile granules. The size and thickness of the layered crystallite are averagely 5 µm and 150 nm, respectively. Their fluorescence microscopy suggests that the BP3T molecules orient standing in the layered crystallites which is a favorable configuration for carrier transportation in OLET and light-amplification in planar crystal cavity.
References
[1] T. Hiramatsu et al. phys. stat. sol. 6, 338-341 (2009)
[2] H. Shimotani et al. The 78th Annual meeting of JSAP, 7a-A203-1 (2017)
[3] S. Dokiya et al., J. of Cryst. Growth, 468, 792 (2017)
[Experiment] In the VFD method, BP3T was first physically vapor-deposited onto a glass substrate. Then, the BP3T/glass sample was placed on the heater, faced up against a SiO2/Si surface, which is spin-coated with fluoropolymer (CYTOP) as a buffer layer. The BP3T/glass was heated at 300°C under a vacuum, then BP3T was transferred onto the SiO2/Si surface.
[Result & Discussion] An atomic force microscopy (AFM) image indicates that the BP3T film transferred onto the SiO2/Si surface and form a layer of the polycrystalline structure while the source film of BP3T on glass is composed of randomly pile granules. The size and thickness of the layered crystallite are averagely 5 µm and 150 nm, respectively. Their fluorescence microscopy suggests that the BP3T molecules orient standing in the layered crystallites which is a favorable configuration for carrier transportation in OLET and light-amplification in planar crystal cavity.
References
[1] T. Hiramatsu et al. phys. stat. sol. 6, 338-341 (2009)
[2] H. Shimotani et al. The 78th Annual meeting of JSAP, 7a-A203-1 (2017)
[3] S. Dokiya et al., J. of Cryst. Growth, 468, 792 (2017)