What can we learn from organic single crystal devices?

Summary form only given. We have shown ambipolar charge transport in high-purity single crystal devices of pentacene (Schon et al, 2000), tetracene, C/sub 60/, /spl alpha/-sexithiophene, and perylene. Mobilities as high as 5.5 cm/sup 2//Vs are achieved in perylene. Inverter circuits and ring oscillators have been prepared using ambipolar FETs. Oscillation frequencies >75 kHz are obtained. Initial results on ambipolar pentacene thin film FETs are presented. The field-effect can be used to inject carriers of both signs into a device. Using two FETs with opposite gate bias, electrons and holes can be injected to generate excitons. We fabricated light-emitting devices and smart pixels on single crystals. High mobilities at low temperatures and balanced injection were found to improve the emission properties of these devices. We also produced photovoltaic devices based on single crystals which have advantages with respect to charge transport properties (Schon et al, 2000). Efficiencies >3% (AM1.5 solar illumination) were achieved.