Oxide semiconductor based thin-fi lm transistors (TFTs) are a promising technology for application in large-area electronics. [ 1 ] Despite their relatively short history, oxide TFTs with chargecarrier mobilities exceeding 100 cm 2 V − 1 s − 1 [ 2,3 ] have already been demonstrated, a performance that is superior to that of amorphous silicon (a-Si) and comparable to polycrystalline Si (poly-Si). Unfortunately, these high-mobility oxide TFTs are usually manufactured using costly vacuum-based processing methodologies. [ 1 , 4-8 ] In an effort to address this problem, recent research has been focussing on the development of TFTs using alternative deposition methods based on solution-processable oxide semiconductors. [ 9 -14 ] Whilst progress on solution-processed oxide semiconductors has been rapidly advancing, research efforts towards the development of new dielectrics has been relatively slow, with most of the reported work performed using conventional dielectrics (e.g., SiO 2 ) with few exceptions. [ 9 , 15,16 ] As a result, the majority of oxide transistors reported to date operate at relatively high voltages and hence consume signifi cantly more power. In order to circumvent this bottleneck, recent work has been focusing on the development of low-voltage oxide transistors, including the use of ultra-thin dielectrics, [ 17 ] high -k dielectrics, [ 15 ] and electrolyte gate dielectrics. [ 18 ] Oxide transistors based on high -k dielectrics have received the most attention and a number of high mobility, low-voltage devices have been demonstrated. [ 15 , 17 ] The high -k materials studied to date include transition metal oxides such as Ta 2 O 5 , TiO 2 , [19][20][21][22] ZrO 2 , [23][24][25][26] Al 2 O 3 , [ 27 ] HfO 2 , [ 28 ] and silicates, [ 29 ] as well as ferroelectric materials such as Pb(Zr,Ti) O 3 and (Ba,Sr)TiO 3 . [ 30 , 31 ] Among these, ZrO 2 and HfO 2 are the most extensively studied dielectrics and are widely considered to be excellent candidates because of their relatively high dielectric constants, good thermal stability, and large band gaps. [32][33][34] Despite their attractive properties, however, ZrO 2 and HfO 2 based TFTs are usually realised using stringent and potentially costly manufacturing techniques. [35][36][37][38][39] Here we demonstrate how spray pyrolysis (SP), a simple and large-area-compatible deposition technique, can be used for the processing of high-quality ZrO 2 layers onto glass substrates containing prepatterned indium tin oxide (ITO) electrodes. We demonstrate their use in high-mobility, low-voltage TFTs based on either ZnO or Li-doped ZnO fi lms deposited by SP [10][11][12][13][14] directly onto ITO/ZrO 2 . Optimised TFTs based on ITO/ZrO 2 / Li-ZnO multilayer structures deposited sequentially at substrate temperatures of 400-450 ° C exhibit excellent electrontransport characteristics with operating voltages below 6 V and a maximum electron mobility on the order of 85 cm 2 V − 1 s − 1 . To our knowledge, this is the highest reported mobility value for transistors bas...

Research on solution processible semiconducting materials is rapidly making progress towards the goal of providing viable alternatives to silicon-based technologies for applications where lower-cost manufacturing and new product features such as mechanical flexibility and optical transparency are desired. One family of materials that has been the subject of intense research over the past twenty years is organic semiconductors.[1] Use of organic materials offers the prospect of low manufacturing cost combined with some desirable physical characteristics such as ease of processing and mechanical flexibility. Despite the impressive progress achieved in recent years a number of obstacles, especially poor air-stability, device performance that is insufficient for a variety of applications and device to device variability, have to be overcome before the advantageous manufacturability, and hence the economic benefits associated with organic semiconductors, can be fully exploited.While research in the area of organic materials and devices has been intensifying, a different class of semiconducting materials, namely metal oxide semiconductors (MOxS), has emerged as possible alternative technology.[2] Metal oxides incorporate important qualities that are currently absent from organic-based semiconductors. For instance, they generally exhibit higher carrier mobilities which are already sufficient for use in optical displays, such as current-driven organic light-emitting diode (OLED) based displays. An additional advantage of MOxS relevant to many electronic applications is the superb optical transparency resulting -2 -from their wide bandgap. The latter makes oxide semiconductors particularly interesting for use in transparent electronics [3] as well as in backplanes for the next generation of currentdriven displays. [4,5] For application in see-through electronics, in particular, transparent thin-film transistors (TFTs) with high switching speeds and low power consumption are required.[6] So far the opacity of amorphous silicon and the insufficient performance of organic semiconductors have impeded the development of such devices. In this respect, MOxS materials simultaneously fulfil the requirements for optical transparency and high charge carrier mobility. In addition, they provide excellent chemical stability combined with mechanical robustness. [7] A further advantage associated with MOxS is the diverse range of techniques that can be employed for thin-film deposition.[7] These include, sputtering, [8][9][10] pulsed-laser deposition (PLD), [11] metalorganic chemical vapour deposition (MOCVD), [12,13] as well as solution processing methods such as dip coating, [14] spin coating [15][16][17][18] and spray pyrolysis (SP). [19][20][21] Solution processing, in particular, offers a number of advantages, which are well known from the area of organic electronics, with the most important being the prospect of easy patterning on large area substrates. In most cases, however, control over the morphology of solution processed film...

The effect of replacing [6,6]-phenyl-C 61 butyric acid methyl ester (PCBM) by its multiadduct analogs (bis-PCBM and tris-PCBM) in bulk heterojunction organic solar cells with poly(3-hexylthiophene-2,5-diyl) (P3HT) is studied in terms of blend film microstructure, photophysics, electron transport properties, and device performance. Although the power conversion efficiency of the blend with bis-PCBM is similar to the blend with PCBM, the performance of the devices with tris-PCBM is considerably lower as a result of small photocurrent. Despite the lower electron affinity of the fullerene multiadducts, ls-ms transient absorption measurements show that the charge generation efficiency is similar for all three fullerenes.The annealed blend films with multiadducts show a lower degree of fullerene aggregation and lower P3HT crystallinity than the annealed blend films with PCBM. We conclude that the reduction in performance is due largely to poorer electron transport in the blend films from higher adducts, due to the poorer fullerene network formation as well as the slower electron transport within the fullerene phase, confirmed here by field effect transistor measurements. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: [45][46][47][48][49][50][51] 2011

Low-voltage organic transistors based on solution processed semiconductors and selfassembled monolayer gate dielectrics Woebkenberg, Paul H.; Ball, James; Kooistra, Floris B.; Hummelen, Jan C.; de Leeuw, Dago M.; Bradley, Donal D. C.; Anthopoulos, Thomas D. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Reduction in the operating voltage of organic transistors is of high importance for successful implementation in low-power electronic applications. Here we report on low-voltage n-channel transistors fabricated employing a combination of soluble organic semiconductors and a self-assembled gate dielectric. The high geometric capacitance of the nanodielectric allows transistor operation below 2 V. Solution processing is enabled by analysis of the surface energy compatibility of the dielectric and semiconductor solutions. Electron mobilities in the range of 0.01-0.04 cm 2 / V s and threshold voltages ഛ0.35 V are demonstrated. The present work paves the way toward solution processable low-voltage/power, organic complementary circuits.

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Interlayer lithography is used to pattern highly conductive, solution‐processed, reduced graphene oxide source and drain electrodes down to 10 μm gaps. These patterned electrodes allow for the fabrication of high‐performance organic thin‐film transistors and complementary circuits. The method offers a viable route towards organic electronics fabricated entirely by solution processing.

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factor of 7. This shows that solution-based silicon is a highly promising candidate for industrial-grade applications of solutionbased semiconductors. Evaluation of Precursors NPS and CPSIn literature, most groups reporting silicon fi lms fabricated from a liquid precursor use a cyclic hydridosilane, namely cyclopentasilane (CPS). We decided to use a branched molecule instead, namely neopentasilane (NPS). The molecular structures of CPS and NPS, as well as the process charts for obtaining solid amorphous silicon (a-Si) layers, are shown in Figure 1 . We characterized the NPS used in our process chain by NMR and by mass spectroscopy, showing the expected fi ngerprints mentioned in literature. [ 4 ] Employing NPS over CPS yields major advantages in processing effi ciency as well as in material quality. In general, branched molecules have a considerably better solubility in organic solvents, because the branches act as spacers, preventing strong interactions between the molecules and enabling better intercalation of solvent molecules. [ 5 ] The NPS material is therefore better soluble than CPS, which leads to improved fi lm homogeneity and uniformity. Moreover, in NMR measurements, we found that the NPS-oligomer bears 70% SiH 3 end groups, in contrast to 1.0% for the CPS-oligomer. Such end groups facilitate the cross-linking of the material to a solid network. Since this process is responsible for the formation of silicon-silicon bonds, we expect a positive effect on the coordination of silicon atoms, resulting in less dangling bonds and improved electronic properties. Until now, we have however not been able to demonstrate differences in nanoscopic amorphous silicon structure between CPS and NPS.Another major advantage of employing NPS instead of CPS lies in the differences in material synthesis. The synthesis of the CPS monomer involves a coupling reaction and subsequent chlorination of diphenyldichlorosilane to obtain decachlorocyclopentasilane. This process produces a large amount of various by-products, which are diffi cult to separate and recycle. However, in the synthesis of NPS, we use catalytic rearrangement of octachlorotrisilane to obtain dodecachloroneopentasilane,