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A solution-processed anthradithiophene derivative, 5,11-bis(4-triethylsilylphenylethynyl)anthradithiophene (TESPE-ADT), is studied for use as the semiconducting material in thin-film transistors (TFTs). To enhance the electrical performance of the devices, two different kinds of solution processing (spin-coating and drop-casting) on various gate dielectrics as well as additional post-treatment are employed on thin films of TESPE-ADT, and p-channel OTFT transport with hole mobilities as high as ~0.12 cm(2) V(-1) s(-1) are achieved. The film morphologies and formed microstructures of the semiconductor films are characterized in terms of film processing conditions and are correlated with variations in device performance.

A series of benzo[d,d]thieno[3,2-b;4,5-b]dithiophene (BTDT) derivatives, end-functionalized with phenyl (P) and benzothiophenyl (BT), were synthesized and characterized. A facile, one-pot synthesis of BTDT was developed which enables the efficient realization of a new BTDT-based semiconductor series for organic thin-film transistors (OTFTs). The crystal structure of P-BTDT was determined via single-crystal X-ray diffraction. Various combinations of dielectric surface treatment methods, substrate temperature, and deposition flux rate sequences have significant effects on device performance. Films deposited on octadecyltrichlorosilane (OTS)-treated SiO2 substrates under properly adjusted substrate temperature and deposition flux rate achieve an efficaceous compromise between high film crystallinity and good film grain interconnectivity, resulting in good OTFT performance, with mobility greater than 0.70 cm2 V−1 s−1 and Ion/Ioff greater than 108.

Four new solution-processable pentacene- (PEN) and anthradithiophene- (ADT) based organic semiconductors bearing two phenylethynyl (PE-) or triethylsilylphenylethynyl (TESPE-) substituents have been synthesized, characterized, and incorporated in thin-film transistors (TFTs). The molecular structures of these four materials have been determined by single-crystal X-ray diffraction. Thin films of all four compounds have been fabricated via drop-casting and exhibited p-channel OTFT transport with hole mobilities as high as ∼0.01 cm2/V s. Compared to PEN derivatives, ADT-based compounds exhibited superior device performance and photooxidative stability in ambient. The film morphologies and microstructures of these compounds have been characterized by optical microscopy and X-ray diffraction to rationalize device performance trends.

The synthesis, single-crystal structures, and device performance of novel naphthalene-diimide are described. The crystal structure has revealed the importance of a withdrawing group on solid-state packing. Metal molybdenum use as source/drain (S/D) electrodes can improve the performance of the bottom-contact device. The bottom-contact device based on a material of N,N′-bis (4-trifluoromethoxybenzyl) naphthalene-1,4,5,8-tetracarboxylic acid diimide has a high mobility of 3.58 × 10−2 cm2 V−1 s−1, a threshold voltage of 1.3 V, and an on/off current ratio of 5.2 × 105.

Three new benzothieno[3,2-b]thiophene (BTT; 1) derivatives, which were end-functionalized with phenyl (BTT-P; 2), benzothiophenyl (BTT-BT; 3), and benzothieno[3,2-b]thiophenyl groups (BBTT; 4; dimer of 1), were synthesized and characterized in organic thin-film transistors (OTFTs). A new and improved synthetic method for BTTs was developed, which enabled the efficient realization of new BTT-based semiconductors. The crystal structure of BBTT was determined by single-crystal X-ray diffraction. Within this family, BBTT, which had the largest conjugation of the BTT derivatives in this study, exhibited the highest p-channel characteristic, with a carrier mobility as high as 0.22 cm(2) V(-1) s(-1) and a current on/off ratio of 1×10(7) , as well as good ambient stability for bottom-contact/bottom-gate OTFT devices. The device characteristics were correlated with the film morphologies and microstructures of the corresponding compounds.

A series of benzo[d,d]thieno[3,2-b;4,5-b]dithiophene (BTDT) derivatives, end-functionalized with phenyl (PBTDT), benzothiophenyl (BT-BTDT) were synthesized and characterized. A facile, one-pot synthesis of BTDT was developed which enables the efficient realization of a new BTDT-based semiconductor series for organic thin-film transistors (OTFTs). The crystal structure of P-BTDT was determined via single-crystal X-ray diffraction. Various combinations of surface treatment methods, substrate temperature, and deposition flux rate sequences have significant effects on device performance. Films deposited on octadecyltrichlorosilane (OTS)- treated SiO 2 substrates under properly adjusted substrate temperature and deposition flux rate achieve an efficaceous compromise between high film crystallinity and good film grain interconnectivity, resulting in good OTFT performance, with mobility greater than 0.70 cm 2 V -1 s -1 and I on /I off greater than 10 8 .

Through incorporating with the technique of rapid polydimethysiloxane (PDMS) lift-off, this study reports on a new laser transfer method that is applicable to printing metallic thin film on a flexible substrate. Aluminum line patterns, with line widths of 40 and 100 µm and deposited on poly(ethylene terephthalate) (PET) substrate, are presented. The patterned film is demonstrated to be a good conductor, with resistivity of 2.95×10−6 Ω-cm, and with very good adhesion strength through the scotch-tape test.

Mono-chrome phosphorescence Organic light emitting diodes (OLEDs) operated by organic thin-film transistors (OTFTs) with a 32×32 array are fabricated with a novel method, and the results reveal a fabulous demonstration. The later isolation, which segregated source/drain electrodes and an OLED cathode, was designed in our OTFT-OLED pixel. In the OTFT-OLED process; we used the polymer isolating layer which was deposited by spin coating and patterned by traditional photo-lithography before the organic semiconductor and OLED deposition. However, the residue polymer affect of OTFT electric properties which have poor mobility (5×10-4 cm2/V-s), a lower on/off ratio (~103), and a positive threshold voltage (4.5 V), and devices, have poor uniformity. Using UV-Ozone treatment could enhance OTFT mobility (2×10-2 cm2/V-s) and permit higher devices uniformity, but the threshold voltage would still have a positive 5.1 V. This threshold voltage was not a good operation mode for display application because this operation voltage was not fit for our driving systems. In order to overcome this problem, a new structure of OTFT-OLED pixel was designed and combined with a new-material isolating layer process. This new process could fabricate an OTFT-OLED array successfully and have a nice uniformity. After the isolating layer process, OTFT devices have a higher mobility (0.1×10-2 cm2/V-s), a higher on-off ratio (~107) a lower threshold voltage (-9.7 V), and a higher devices uniformity.

An abnormal sub-threshold leakage current is observed at high temperature in amorphous indium-gallium-zinc-oxide thin film transistors (a-IGZO TFTs). This phenomenon occurs due to a reduced number of defects in the device's a-IGZO active layer after the device has undergone N2O plasma treatment. Experimental verification shows that the N2O plasma treatment enhances the thin film bonding strength, thereby suppressing the formation of temperature-dependent holes, which are generated above 400 K by oxygen atoms leaving their original sites. The N2O plasma treatment devices have better stability performance than as-fabricated devices. The results suggest that the density of defects for a-IGZO TFTs with N2O plasma treatment is much lower than that in as-fabricated devices. The N2O plasma treatment repairs the defects and suppresses temperature-dependent sub-threshold leakage current.