Effect of photoinduced charge displacement on organic optoelectronic conversion

As a significant drawback to organic electronics, poor mobility in organic materials makes it difficult for carriers to make long trips across thin film devices. In the present work, we show that a short carrier trip or even charge displacement can contribute to the functioning of optoelectronics without being influenced by the poor carrier mobility. Our findings are based on analysis of the current-voltage and capacitance-voltage characteristics, as well as the anomalous transient photocurrent of the photocells of a radical material, 4'4-bis(1,2,3,5-dithiadiazolyl). This photoinduced transient current was successfully analyzed based on the total current equation and was interpreted in terms of the polarization current induced by charge displacement in the films. This mechanism provides preliminary information with respect to the development of methods for high-speed organic optoelectronic conversion.