Dmitry Yu. Paraschuk: Toward ultrathin crazy shining semiconducting organics

Emerging organic light-emitting field-effect devices, such as light-emitting transistors and electrically-pumped lasers, need ultrathin thin films combining bright luminescence and efficient charge transport. An ideal solution would be 100% emissive semiconducting single-crystal monolayers. However, if emissive molecules are aggregated to sustain charge transport, their luminescence is usually quenched. This hurdle is generally resolved by doping the host material by highly luminescent molecules collecting the excitation energy from the host. Using thiophene-phenylene co-oligomers (TPCO), we present а novel concept of molecular self-doping in which a higher luminescent dopant emerges as a minute-amount byproduct during the host material synthesis. On the other hand, alkyl-functionalized TPCO are easily organized in 2D single crystals. We have found that ordered two-dimensional (2D) crystalline packing of TPCO is compatible with its high-yield luminescence and provides efficient charge transport. We believe that molecular self-doping combined the rational design of functional materials for monolayer organic field-effect devices is a promising platform for totally emissive ultrathin semiconducting organics.