Unraveling the Charge-Carrier Dynamics from the Femtosecond to the Microsecond Time Scale in Double-Cable Polymer-Based Single-Component Organic Solar Cells

Abstract

Single-component organic solar cells (SCOSCs) have witnessed great improvement during the last few years with the champion efficiency jumping from the previous 2–3% to currently 6–11% for the representative material classes. However, the photophysics in many of these materials has not been sufficiently investigated, lacking essential information regarding charge-carrier dynamics as a function of microstructure, which is highly demanded for a better understanding and potential guidance for further improvements. In this work, for the first time, the charge-carrier dynamics of a representative double-cable polymer, which achieves efficiencies of over 6% as an active layer in SCOSCs, is investigated across seven orders of magnitude in time scale, from fs–ps charge generation to ns–µs charge recombination processes. Specific emphasis is placed on understanding the impact of thermal post-treatment on the charge dissociation and recombination dynamics. Annealing the photoactive layer at 230 °C results in the highest photovoltaic performance because of efficient charge generation in parallel to suppressed recombination. This work intends to present a complete picture of the charge-carrier dynamics in SCOSCs using the representative double-cable polymer PBDBPBI-Cl.