Design Strategy for Robust Organic Semiconductor Laser Dyes

A new molecular design for organic semiconductor laser dyes showing excellent optical properties and high robustness is disclosed in this work. The suitability of a furan moiety for increasing the thermal and photostability in newly developed furan-based derivatives (BPBFCz) is demonstrated by comparing a well-known laser molecule (BSBCz) having a bis-stilbene unit. The new derivatives exhibited high photoluminescence quantum yields of nearly 100% and radiative rate constants of ∼10 9 s –1 in both solution and doped films, and their properties were also excellent in neat films. The amplified spontaneous emission (ASE) thresholds of the BPBFCz materials were found to be very low (<1 μJ cm –2 ), and the excited-state absorption in the ASE oscillation region was negligible, which is preferable for laser applications. In addition to these excellent optical properties, which are comparable or superior to those of BSBCz, the decomposition temperatures of the BPBFCz emitters were much higher than that of BSBCz, resulting in the suppression of impurity formation during the thermal deposition. In addition, the photostability of the new materials was dramatically improved compared with that of BSBCz. This study serves as a very significant advancement toward the practical application of organic semiconductor laser diodes and provides molecular design guidelines for robust organic laser molecules.