Year: 2015
Type: article
Abstract: Incorporation of electrotropic additives with large molecular dipole moments into the bulk heterojunction layer of organic photovoltaic devices followed by electric field poling led to an increase of power conversion efficiency up to 7.97% from 7.17% for devices that did not utilize the additives and from 5.18% for devices with additives prior to poling. The improvement is due to more efficient extraction of photogenerated charge carriers, resulting in higher short circuit current density and fill factor. The observed effects are proposed to arise from a re-orientation of additive molecules in the external electric field, i.e., electrotropism, leading to a macroscopic alignment of their dipole moments. This leads to an increased built-in electrostatic potential difference in the device active layer post-poling. The dependence of device performance on the polarity of poling bias and reversibility of the effect are demonstrated, further supporting the proposed mechanism.
Source: Applied Physics Letters
DOI: 10.1063/1.4914847
Institution: University of Massachusetts Amherst
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2011936411