Temperature dependent photoluminescence of organic semiconductors with varying backbone conformation

TL;DR

This study investigates how temperature affects the photoluminescence of various organic semiconductors with different backbone conformations, revealing distinct shifts in emission energies linked to molecular structure.

Contribution

It provides a comparative analysis of temperature-dependent photoluminescence in conjugated polymers and molecules with different backbone conformations, extending empirical models from inorganic semiconductors.

Findings

Long-chain polymers exhibit blue shifts in emission with increasing temperature.

Conjugated molecules show red shifts in emission with increasing temperature.

Empirical models can be applied to explain temperature effects in organic semiconductors.

Abstract

We present photoluminescence studies as a function of temperature from a series of conjugated polymers and a conjugated molecule with distinctly different backbone conformations. The organic materials investigated here are: planar methylated ladder type poly para-phenylene, semi-planar polyfluorene, and non-planar para hexaphenyl. In the longer-chain polymers the photoluminescence transition energies blue shift with increasing temperatures. The conjugated molecules, on the other hand, red shift their transition energies with increasing temperatures. Empirical models that explain the temperature dependence of the band gap energies in inorganic semiconductors can be extended to explain the temperature dependence of the transition energies in conjugated molecules.