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The present work addresses several issues in the field of organic and transparentelectronics. One of them is the prevailing high power consumption in state-of-the-artorganic field-effect transistors (OFETs). A possible solution could be theimplementation of complementary, rather than unipolar logic, but this development iscurrently inhibited by a distinct lack of high performance electron transporting (n-channel)OFETs. Here, the issue is addressed by investigating a series of solutionprocessable n-channel fullerene molecules in combination with optimized transistorarchitectures. Furthermore, the trend towards complementary circuit design could befacilitated by employing ambipolar organic semiconductors, such as squarainemolecules or polymer/fullerene blends. These materials can fill the role of p- or n-channelsemiconductors and enable the facile implementation of power savingcomplementary-like logic, eliminating the cost-intensive patterned deposition ofdiscrete p-and n-channel transistors. Alternatively, a patterning method for organicmaterials adapted from standard photolithography is discussed. Furthermore,ambipolar FETs are found to be capable of light sensing at wavelength of 400-1000nm. Hence their use in low-cost, organic based optical sensor arrays can be envisioned.Another strategy to reduce the power consumption and operating voltages ofOFETs is the use of ultra-thin, self-assembled molecular gate dielectrics, such asalkyl-phosphonic acid molecules. Based on this approach solution processed n- and p-channelOFETs and a complementary organic inverter circuit are demonstrated, whichoperate at less than 2 Volts.Finally, transparent oxide semiconductors are investigated for use in thin-filmtransistors. Titanium dioxide (TiO2) and zinc oxide (ZnO) films are deposited bymeans of a low-cost large area compatible spray pyrolysis technique. ZnO transistorsexhibit high electron mobility of the order of 10 cm2/Vs and stable operation in air atless than 2 Volts. These results are considered significant steps towards thedevelopment of organic and transparent large-area optoelectronics. Imperial Users only

The present work addresses several issues in the field of organic and transparent electronics. One of them is the prevailing high power consumption in state-of-the-art organic field-effect transistors (OFETs). A possible solution could be the implementation of complementary, rather than unipolar logic, but this development is currently inhibited by a distinct lack of high performance electron transporting (n-channel) OFETs. Here, the issue is addressed by investigating a series of solution processable n-channel fullerene molecules in combination with optimized transistor architectures. Furthermore, the trend towards complementary circuit design could be facilitated by employing ambipolar organic semiconductors, such as squaraine molecules or polymer/fullerene blends. These materials can fill the role of p- or n-channel semiconductors and enable the facile implementation of power saving complementary-like logic, eliminating the cost-intensive patterned deposition of discrete p-and n-channel transistors. Alternatively, a patterning method for organic materials adapted from standard photolithography is discussed. Furthermore, ambipolar FETs are found to be capable of light sensing at wavelength of 400-1000 nm. Hence their use in low-cost, organic based optical sensor arrays can be envisioned. Another strategy to reduce the power consumption and operating voltages of OFETs is the use of ultra-thin, self-assembled molecular gate dielectrics, such as alkyl-phosphonic acid molecules. Based on this approach solution processed n- and p-channel OFETs and a complementary organic inverter circuit are demonstrated, which operate at less than 2 Volts. Finally, transparent oxide semiconductors are investigated for use in thin-film transistors. Titanium dioxide (TiO2) and zinc oxide (ZnO) films are deposited by means of a low-cost large area compatible spray pyrolysis technique. ZnO transistors exhibit high electron mobility of the order of 10 cm2/Vs and stable operation in air at less than 2 Volts. These results are considered significant steps towards the development of organic and transparent large-area optoelectronics.

We report on electron transporting organic transistors and integrated ring oscillators based on four different solution processible fluorine containing C(60) derivatives. Electron mobilities up to 0.15 cm(2)/V s are obtained from as-prepared bottom-gate, bottom-contact transistors utilizing gold source-drain electrodes. Despite the high mobility, no long-range structural order could be identified with the semiconductor films exhibiting amorphouslike characteristics. The good electron transport is attributed to the structural symmetry of the fullerene derivatives and the enhanced pi-pi interactions between C(60) units even in the case of amorphouslike films. These advantageous characteristics make fluorine containing C(60) derivatives attractive for application in high-performance, large-area organic electronics. (C) 2008 American Institute of Physics.