Substrate Effects on the Bandwidth of CdSe Quantum Dot Photodetectors

We investigate the time-resolved photocurrent response of CdSe quantum dot (QD) thin films sensitized with zinc β-tetraaminophthalocyanine (Zn4APc) (Kumar , ACS Appl. Mater. Interfaces, 2019, 11, 48271-48280) on three different substrates, namely, silicon 230 nm SiO2 dielectric, glass, and polyimide. While Si/SiO2 (230 nm) is not suitable for any transient characterization due to an interfering buried silicon, we find that polyimide substrates invoke larger optical bandwidth 85 kHz vs 67 same film glass. Upon evaluation photocurrent, photoresponse can be described as a combination carrier recombination fast trapping within 2.7 ns followed by slower multiple events. The latter are less pronounced polyimide, which leads higher bandwidth. show all devices resistance-capacitance (RC)-time limited improvements photoresistance key further increasing