Cyano-substituted oligo(p-phenylene vinylene) single crystals: A promising laser material

Organic crystals that combine high charge-carrier mobility and excellent light-emission characteristics are expected to be of interest for light-emitting transistors and diodes, and may offer renewed hope for electrically pumped laser action. High-luminescence-efficiency cyano-substituted oligo(p- phenylene vinylene) (CN-DPDSB) crystals (η ≈ 95%) grown by the physical vapor transport method is reported here, with high mobilities (at ≈10^-2 cm² V^-1 s^-1 order of magnitude) as measured by time-of-flight. The CN-DPDSB crystals have well-balanced bipolar carrier-transport characteristics (μ_hole≈ 2.5-5.5 × 10^-2 cm² V^-1 s^-1; μ_electron ≈ 0.9-1.3 × 10^-2 cm² V^-1 s^-1) and excellent optically pumped laser properties. The threshold for amplified spontaneous emission (ASE) is about 4.6 μJ per pulse (23 KW cm^-2), while the gain coefficient at the peak wavelength of ASE and the loss coefficient caused by scattering are ≈35 and ≈1.7 cm^-1, respectively. This indicates that CN-DPDSB crystals are promising candidates for organic laser diodes.