Improving the current stability of perovskite quantum dot phototransistors utilizing the ferrocene–cyclodextrin host–guest supramolecules as a floating gate dielectric†

Abstract

Photodetectors have garnered significant attention due to their vital role in a wide range of applications, including optical communication, environmental monitoring, and imaging technologies. However, the design and optimization of high-performance photodetector materials remain an ongoing challenge. In this study, a novel electroactive supramolecular floating-gate layer is developed by utilizing host–guest interactions between β-cyclodextrin (β-CD) and ferrocene. This supramolecular structure is integrated into a phototransistor as the floating gate dielectric to enhance photoresponse capabilities, facilitating rapid photoresponse due to its efficient charge transport properties, which minimize charge accumulation. Furthermore, the incorporation of perovskite quantum dots (QDs) enhances the device's optical response. With the optimal supramolecular composition of 5 wt% β-CD-modified QDs in the ferrocene-functionalized polymer to form host–guest supramolecules, the transient photocurrent response confirms its superior performance, with shorter rise and fall times (0.18 s and 2.1 s, respectively), prolonged current stability (10⁴ s and extrapolated to 10⁹ s), and a low photo-/dark-current of approximately 10⁻⁸ and 10⁻¹¹ A, which are favorable for low power-consumption photodetectors. The improvements in the supramolecular films can be attributed to their smooth and homogeneous morphologies, as well as fast charge-transfer kinetics, which ensure uniform carrier transport and counter-charge trapping, leading to efficient and stable photoinduced charge generation. This study reveals the potential functionality of host–guest interaction in enhancing the phototransistor's performance due to the size complementarity of ferrocene and β-CD, which preorganizes QD allocations in the supramolecular floating gate.