Effect of Polymer Blend on Electrical Performance and Photo-Response of TIPS-Pentacene OFETs
01 Oct 2019-
TL;DR: In this paper, the effect of TIPSpentacene: polystyrene (PS) blend on electrical performance and photo-response of solution processed organic field effect transistors (OFETs) was explored.
Abstract: In this work, we have explored the effect of TIPSpentacene: polystyrene (PS) blend on electrical performance and photo-response of solution processed organic field-effect transistors (OFETs). It was observed that though the blend OFETs show better electrical performance, the photo-responsivity (R) of neat TIPS-pentacene OFETs was significantly better. This study was performed for different color lights such as blue, red, and green, as well as for ultraviolet light (UV). R was highest for blue color (~2600 mA/W for neat, ~230 mA/W for blend), and smaller for other cases. Low R value in blend devices is attributed to less trapping of photo-generated charge carriers during photo-illumination compared to their neat counterparts.
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TL;DR: The solvent from which the active layer is drop cast dramatically influences the electrical characteristics and electrical stability of thin-film transistors comprising bis(triisopropylsilylethynyl) pentacene as mentioned in this paper.
Abstract: The solvent from which the active layer is drop cast dramatically influences the electrical characteristics and electrical stability of thin-film transistors comprising bis(triisopropylsilylethynyl) pentacene. Casting from high boiling solvents allows slower crystallization; devices cast from toluene and chlorobenzene thus exhibit mobilities >0.1 cm2/V s and on/off ratios of ∼106. More importantly, the solvent choice influences the device stability. Devices from toluene exhibit stable characteristics, whereas devices from chlorobenzene show hystereses on cycling, with dramatic threshold voltage shifts toward positive voltages. The instability in chlorobenzene devices is attributed to the migration of water and solvent impurities to the charge transport interface on repetitive testing.
124 citations
TL;DR: In this article, a systematic study of solvent and polymer matrix effects on the phase segregation behavior of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) blends incorporated into two different amorphous polymer matrices, poly (α-methyl styrene) and poly (triarylamine), and using two solvents, chlorobenzene and tetralin, was performed.
Abstract: We report on a systematic study of solvent and polymer matrix effects on the phase segregation behavior of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) blends incorporated into two different amorphous polymer matrices, poly (α-methyl styrene) and poly (triarylamine), and using two solvents, chlorobenzene and tetralin. Optical microscopy, X-ray diffraction analyses, and optical absorption measurements are used to evaluate the film morphology, crystallinity, and optical density, respectively. These analyses are correlated with the extent of vertical segregation of TIPS-pentacene, as observed for the blended films by depth-profile XPS analyses. The microstructure and vertical phase segregation of TIPS-pentacene in blend films are found to be strongly influenced by the choice of solvent. Tetralin, a solvent with a high boiling temperature, was found to be more desirable for achieving distinct phase segregation/crystallization of TIPS-pentacene in blend films and best performance in OFETs with a dual-gate geometry. The electrical properties of top and bottom channels were consistent with the morphological characterization and OFETs processed from tetralin showed higher mobility values than those from chlorobenzene. Further modification of the annealing conditions in the TIPS-pentacene/PTAA/tetralin ternary system led to top-gate OFETs with mobility values up to 2.82 cm2/Vs.
114 citations
TL;DR: In this article, the authors demonstrated that by taking advantage of the interfacial charge effect, printable and flexible organic phototransistors with high performance can be successfully fabricated through simply blending common OSCs with polymers.
Abstract: Printable and flexible organic phototransistors (OPTs) make comprehensive requirements for the organic semiconductors (OSCs), including high photosensitivity, decent transistor characteristics, appropriate solution viscosity, and good film flexibility. It has been challenging to obtain such semiconductors. Here, we demonstrated that by taking advantage of the interfacial charge effect, printable and flexible OPTs with high performance can be successfully fabricated through simply blending common OSCs with polymers. Using 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene and an insulating biopolymer polylactide, OPTs with blended and layered structure are both fabricated and investigated. The photoresponses of the OPTs can be modulated by gate voltage over 1000 times, and their responsivities are measured up to 400 A W−1. As compared to the layered OPTs, the blended ones exhibit higher photocurrent to dark current ratio (up to 105) and better light detection limit (lower than 0.02 mW cm−2). The improvements are attributed to larger interfacial area and more intensive charge trapping effect. The flexible OPTs are further fabricated by inkjet printing the blended solution. This work presents OPTs with comprehensive advantages including low cost, enhanced photosensitivity, great flexibility, and printability, which are realized by simply blending common OSC with polymer, and thus provide an inspiration for the design of novel organic electronics.
73 citations
TL;DR: In this article, the phototransistors with pentacene semiconductor and Ta2O5 or polymethyl methacrylate (PMMA) dielectric layer have been investigated.
Abstract: Organic phototransistors with pentacene semiconductor and Ta2O5 or polymethyl methacrylate (PMMA) dielectric layer have been investigated. It was found that the phototransistor properties strongly depend on the dielectric layer. Under a broadband light with 10mW∕cm2, the sensitivity of the Ta2O5 based transistor is much higher than that of the PMMA based transistor. For Ta2O5 based transistor, the photosensitivity (the ratio of photocurrent to dark current) and the threshold voltage shift are 4000 and 13.5V, respectively. While for PMMA based transistor, the corresponding values are only 0.5 and 2.9V, respectively. That large difference is attributed to the electron trapping ability of Ta2O5.
66 citations
TL;DR: High-performance operationally stable organic field-effect transistors were successfully fabricated on a PowerCoat HD 230 paper substrate with a TIPS-pentacene:polystyrene blend as the active layer and poly(4-vinylphenol)/HfO2 as the hybrid gate dielectric and exhibited remarkable stability under effects of gate bias stress and large number of repeated transfer scans with negligible performance spread.
Abstract: High-performance operationally stable organic field-effect transistors were successfully fabricated on a PowerCoat HD 230 paper substrate with a TIPS-pentacene:polystyrene blend as the active layer and poly(4-vinylphenol)/HfO2 as the hybrid gate dielectric. The fabricated devices exhibited excellent p-channel characteristics with a maximum and av field effect mobility of 0.44 and 0.22(±0.11) cm2 V–1 s–1, respectively, av threshold voltage of 0.021(±0.63) V, and current on–off ratio of ∼105 while operating at −10 V. These devices exhibited remarkable stability under effects of gate bias stress and large number of repeated transfer scans with negligible performance spread. In addition, these devices displayed very stable electrical characteristics after long exposure periods to humidity and an excellent shelf life of more than 6 months in ambient environment. Thermal stress at high temperatures however deteriorates the device characteristics because of the generation and propagation of cracks in the active ...
46 citations