Browsing by Author "Chen, Li-Ming"

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A cascade energy band structure enhances the carrier energy in organic vertical-type triodes
(2013-09-01)
Cheng, Shiau-Shin
;
Ramesh, Mohan
;
Chen, Guan-Yuan
;
Fung, Chun-Lin
;
Chen, Li-Ming
Organic vertical-type triodes (OVTs) based on the cascade energy band structure as emitter layer are studied. The electric characteristics were dramatically enhanced while incorporating the cascade energy under current driving and voltage driving modes. The improvement is attributed to that injection carriers can obtain higher energy through a stepwise energy level. When the device has a layered structure of F16CuPC (10 nm)/PTCDI (10 nm)/pentacene (100 nm) in emitter, it exhibits a common-base transport factor of 0.99 and a common-emitter current gain of 225 under current driving mode and exhibits a high current modulation-exceeding -520 mu A for a low collector voltage of -5 V and a base voltage of -5 V and the current on/off ratio of 10(3) under voltage driving mode. Furthermore, we realized first organic current mirror that exhibited out/in current ratio of 0.75 and output resistance of 10(5) Omega by using the OVTs. (C) 2013 Published by Elsevier B.V.
Solution-Processed Small-Molecule Bulk Heterojunction Ambipolar Transistors
(2014-04-01)
Cheng, Shiau-Shin
;
Huang, Peng-Yi
;
Ramesh, Mohan
;
Chang, Hsiu-Chieh
;
Chen, Li-Ming
Solution-processed small-molecule bulk heterojunction (BHJ) ambipolar organic thin-film transistors are fabricated based on a combination of [2-phenylbenzo[d,d \']thieno[3,2-b;4,5-b \']dithiophene (P-BTDT) : 2-(4-n-octylphenyl)benzo[d,(d) under bar \']thieno[3,2-b;4,5-b\']dithiophene (OP-BTDT)] and C-60. Treating high electrical performance vacuum-deposited P-BTDT organic semiconductors with a newly developed solution-processed organic semiconductor material, OP-BTDT, in an optimized ratio yields a solution-processed p-channel organic semiconductor blend with carrier mobility as high as 0.65 cm(2) V-1 s(-1). An optimized blending of P-BTDT:OP-BTDT with the n-channel semiconductor, C-60, results in a BHJ ambipolar transistor with balanced carrier mobilities for holes and electrons of 0.03 and 0.02 cm(2) V-1 s(-1), respectively. Furthermore, a complementary-like inverter composed of two ambipolar thin-film transistors is demonstrated, which achieves a gain of 115.