Organic light-emitting transistors (OLETs) are promising components for optoelectronics, smart display technologies, and electrically pumped lasers. They combine the light-emitting function of organic light-emitting diodes (OLEDs) and the current modulation (and signal amplification) function of organic field-effect transistors (OFETs) in a single device. High-mobility emissive organic semiconductors with tunable colors, which serve as the core active layer in OLETs, must be developed to advance these technologies.
Using a molecular doping strategy, a research team created a series of color-tunable, high-mobility, emissive organic semiconductors. Well-matched molecular structures and sizes and efficient energy transfer between the host and guest enable intrinsically high charge transport properties with tunable colors.
The fluorescence spectra of molecularly doped single crystals show that the degree of energy transfer increases as doping concentration increases.
The molecular doped organic light-emitting transistors exhibit strong and spatially controlled electroluminescence in both P-channel and N-channel. It is due to the high mobility and emissivity of the doped crystals and the asymmetric electrode device structure. Their low hysteresis and maximum photocurrent switching ratio demonstrate their excellent optoelectronic performance in the molecular doped single-crystal OLETs devices.
It is possible to extend the strategy to more conjugated organic molecule systems by rationally selecting a high-mobility host and guest molecules.