Initial Photocarrier Generation Process in Organic Photovoltaics Observed with Light-Triggered Time-Domain Reflectometry

Herein, a time-resolved electrical measurement is developed to observe the transient impedance of organic photovoltaics (OPV) and traced the initial photocarrier generation dynamics with the time region from 10 ns to 190 & mu;s. A light-triggered time-domain reflectometry is adopted to observe the initial carrier dynamics in OPV by synchronizing rectangular light pulses from LED with a transient impedance probe pulse. Both the rising and recovery processes of OPV are observed in detail. The time evolution of the photocarrier distribution is calculated based on the diffusion-recombination scheme and is discussed in the initial process of photocarrier generation.