ABSTRACT
This chapter presents the separation, recombination, and transport of charge carriers in conjugated-polymer:fullerene organic photovoltaics (OPV) revealed by using flash-photolysis time-resolved microwave conductivity (TRMC). This technique provides a direct access to inherent optoelectronics without electrodes, envisioning the wide prospect of TRMC in detailing charge-carrier dynamics. A bulk heterojunction (BHJ) framework greatly benefits the efficient migration of exciton to the donor–acceptor interface and prevents non-geminate charge recombination (CR) in OPV devices. The chapter explains how the contrasting polymer orientation affects the charge separation (CS) and CR at the polymer/fullerene heterojunction and how the polymer crystallinity moderates the hole mobility during transport from the bottom to the top of the BHJ layer. Charge-carrier mobility is a crucial parameter for electronic devices, which determines current flow and a balance of positive and negative charges; it is associated with the CS at the donor–acceptor interface.
