Light Amplification and Efficient Electroluminescence from a Solution?Processable Diketopyrrolopyrrole Derivative via Triplet?to?Singlet Upconversion

Over the years, achieving efficient electroluminescence (EL) while simultaneously having low light amplification thresholds under optical excitation has been key to progression toward long-thought objective of electrically pumped organic lasers. While significant progress in this regard made for semiconductors emitting blue–green region visible spectrum, laser dyes with low-energy emission (>600 nm) still suffer from high amplified spontaneous (ASE) and external quantum efficiencies (EQEs) devices. Herein, ASE EL are reported a solution-processable dye dithiophenyl diketopyrrolopyrrole (DT-DPP). The threshold 4 µJ cm?2 at wavelength 620 nm is obtained making constructive use triplet excitons by doping DT-DPP green-emitting host matrix, which exhibits thermally activated delayed fluorescence (TADF). light-emitting diode fabricated system gives EQE 7.9% due utilization excitons. Transient studies further show that reverse intersystem crossing rate crucial lasing electrical pumping such TADF-assisted fluorescent systems.