Effect of traps on carrier transport in CdSe quantum dot thin films

Abstract

The influence of trap effects on carrier transport characteristics in quantum dot (QD) thin films is the subject of study, aiming to provide a theoretical basis for the structural design and performance improvement of QD thin film optoelectronic devices. This study presents a specific mathematical description of capturing and releasing charges by traps, which includes the time-varying equation for captured charges. Utilizing the carrier hopping transport model, a system of partial differential equations is employed as the physical field, establishing hopping transport models that account for both shallow traps and a combination of shallow and deep traps. Simulations based on specific experimental samples reveal that the presence of traps introduces asymmetry in the diffusion motion of charge carriers, extending the duration of the photocurrent signal and resulting in the capture of charges, along with a reduction in the peak value of the current signal. The model also simulates carrier transport characteristics under the influence of repetitive light pulses, demonstrating distinct patterns in capturing and releasing charges for both shallow and deep traps.