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.