Direct Measurement of Electric Field‐Assisted Charge Separation in Polymer:Fullerene Photovoltaic Diodes

The electric field dependence of transient optical absorption of photogenerated charge carriers in working organic photovoltaic cells is reported. Charge lifetimes are extended under reverse bias, revealing that the mechanism of photocurrent generation is the electric field-assisted separation of Coulombically bound charge pairs in kinetic competition with geminate charge recombination. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.