Exciton management and balanced charge-carrier transport enable efficient organic field-effect light-emitting transistors

Organic light-emitting transistors integrate the switching ability of a transistor with the emissive property of an organic light-emitting diode. Among them, organic field-effect light-emitting transistors (OFE-LETs) have recently gained increasing attention due to their simplified device structure, low leakage current and ease of integration. However, OFE-LETs often suffer from unbalanced electron and hole transport, leading to a low radiative recombination efficiency in the emissive layer and low device efficiency. Here we present a promising device architecture in which the functions of charge-carrier transport and light emission are spatially separated, enabling precise exciton management. The use of carbazole/oxadiazole hybrid molecules coupled with a strong electron-withdrawing cyano moiety results in balanced charge-carrier transport, creating a broad exciton recombination zone and enhancing the radiative recombination efficiency. Accordingly, red, green and blue OFE-LETs achieve peak external quantum efficiencies of 18.4, 21.2 and 14.4%, and current efficiencies of 26.9, 78.0 and 31.7 cd A⁻¹, respectively. These values rank among the highest for organic light-emitting transistors so far. Furthermore, the patterned OFE-LET arrays with an aperture ratio of over 60% and pixel circuits that exhibit only 5.6% parasitic power dissipation demonstrate promising potential for low-power-consumption display technologies.