Photoeffect in polythiopentacene films and influence of permanent illumination on it

TL;DR

This study investigates the internal photoeffect in polythiopentacene films, revealing how illumination influences photo-emf and charge dynamics, with implications for optoelectronic device behavior.

Contribution

It provides new insights into the spectral dependence of photo-emf and the effects of illumination on charge polarity and transport in polythiopentacene films.

Findings

Spectral dependence of Vf correlates with PTP absorption spectrum.

Back photo-emf Vb anticorrelates with PTP absorption spectrum.

Illumination alters the polarity of Vb and affects charge transport.

Abstract

The internal photoeffect in polythiopentacene (PTP) films is investigated. It is discovered that, in capacitor cells, the spectral dependence of the frontal photo-emf Vf correlates with the PTP absorption spectrum, while that of the back photo-emf Vb anticorrelates with it. The polarities of Vf and Vb coincide. In this case, the charge of the free PTP surface is negative, whereas that of the frontal SnO2 electrode is positive. Back low- and strong-absorption illuminations photogenerate holes that diffuse to the free PTP surface and decrease Vdf . These illuminations change the polarity of Vb. The spectra of the density of short-circuit current Jsc of the sandwich cells SnO2 PTPAg and Vb correlate. Under the modulated illumination of these cells through the SnO2 and Ag electrodes, the drift flow of nonequilibrium holes in the electric field, conditioned by the antiblocking bending of the PTP bands near these electrodes, prevails.