Semiconducting (Conjugated) Polymers as Materials for Solid-State Lasers

Abstract

Light‐emissive polymers are outstanding laser materials because they are intrinsically “4‐level” systems, they have luminescence efficiencies higher than 60 % even in undiluted films, they emit at colors that span the visible spectrum, and they can be processed into optical quality films by spin casting. The important materials issues are reviewed and the prospects for making polymer diode lasers are discussed.

Low-threshold organic laser based on an oligofluorene truxene with low optical losses

“…1-3 New materials are being synthesized that offer improvements in key photophysical properties such as photoluminescence quantum yield ͑PLQY͒, optical gains and optical losses, leading to organic lasers with lower lasing thresholds. [4][5][6][7][8] Most of the research in the field revolves around creating materials with higher optical gain per unit length, as this allows for stronger amplification of the emitted light that increases the output of a laser and reduces the lasing threshold. 4 The optical losses that light experiences as it travels through an organic thin film are equally important as they significantly affect the lasing threshold and efficiency but have been investigated to a lesser degree than optical gain and usually in the context of the additional losses introduced by metal contacts for electrical excitation of organic films.…”

Structure—Property relationships for exciton transfer in conjugated polymers

“…1 Many CPs have an extremely large absorption cross-section (r % 10 À15 cm 2 ) because the p!p* transition is allowed and the quasi one-dimensional electronic wavefunctions have a high density of states at the band edge. 2 Additionally, a CP can exhibit strong luminescence depending on the system. The luminescence efficiency is primarily related to the delocalization and polarization of the electronic structure of the CP.…”

Thiophene–phenylene/naphthalene‐based step‐ladder copolymers

“…Dry toluene (2 mL) and dry DMF (1 mL) were added and the solutions irradiated with microwaves (300 W, 110 C) for 15 min. The reaction mixture was diluted with chloroform and washed with aqueous 2 N HCl, saturated aqueous NaHCO 3 and NaEDTA solutions and brine. The organic phase was dried over Na 2 SO 4 and the solvent removed in vacuo.…”

“…Phenylene-and thiophene-based materials belong to the most extensively studied classes of conjugated molecules for use in organic electronic devices such as light-emitting diodes, 1,2 polymer lasers, 3 field-effect transistors, 4 and polymer solar cells 5,6 Unsubstituted oligomers of a certain length are generally completely insoluble in organic solvents and require vacuum deposition. However, for large area devices, solution-processable materials are needed.…”