Quantum dot and electron acceptor nano-heterojunction for photo-induced capacitive charge-transfer

Abstract

Capacitive charge transfer at the electrode/electrolyte interface is a biocompatible mechanism for the stimulation of neurons. Although quantum dots showed their potential for photostimulation device architectures, dominant photoelectrochemical charge transfer combined with heavy-metal content in such architectures hinders their safe use. In this study, we demonstrate heavy-metal-free quantum dot-based nano-heterojunction devices that generate capacitive photoresponse. For that, we formed a novel form of nano-heterojunctions using type-II InP/ZnO/ZnS core/shell/shell quantum dot as the donor and a fullerene derivative of PCBM as the electron acceptor. The reduced electron–hole wavefunction overlap of 0.52 due to type-II band alignment of the quantum dot and the passivation of the trap states indicated by the high photoluminescence quantum yield of 70% led to the domination of photoinduced capacitive charge transfer at an optimum donor–acceptor ratio. This study paves the way toward safe and efficient nanoengineered quantum dot-based next-generation photostimulation devices.

Role of Copper Doping in Heavy Metal‐Free InP/ZnSe Core/Shell Quantum Dots for Highly Efficient and Stable Photoelectrochemical Cell

“…[5b] Recently, Nizamoglu and coworkers developed nano-heterostructured PEC devices based on InP/ZnS and InP/ ZnO/ZnS QDs, showing a maximum photocurrent density of 120 µA cm −2 under light irradiation. [10] Such low performance of InP core/shell QDs-PEC devices could be due to the type I band structure of InP/ZnSe (ZnS) core/shell QDs that confines the photoexcited electron-hole pairs within the core, thus restricting the extraction of photo-induced electrons in QDs for consequent energy conversion.…”

RuO2 Supercapacitor Enables Flexible, Safe, and Efficient Optoelectronic Neural Interface

“…ZnO layer serves as the hole blocker due to its valence band energy level and electron transporter owing to its high electron mobility. [ 20 ] The device design consists of ZnO/P3HT:PCBM layer over 1 cm 2 area of the ITO‐coated substrate and electrodeposited RuO 2 film over the remaining 0.5 cm 2 area of the same substrate ( Figure a). The control devices are bare ITO as the return electrode without RuO 2 coating.…”

Cadmium-Free and Efficient Type-II InP/ZnO/ZnS Quantum Dots and Their Application for LEDs

“…For the InP core QDs, the In 3d spectrum exhibits two peaks located at 444.5 eV (3d 5/2 ) and 452.1 eV (3d 3/2 ) (Figure g,h), which can be assigned to InP. − The P 2p spectrum shows two doublets, which are related to the two different chemical environments of the phosphorus atoms. The first pre-dominant doublet that occurs at 127.8–128.9 eV (2p 3/2 ) is the characteristic peak for InP. , The doublet in the 132.4–133.4 eV range is associated with the P atoms in an oxidized medium, most probably InPO X . , In the XPS spectra of InP/ZnO core/shell QDs, the peaks corresponding to Zn 2p are observed which indicates the Zn 2+ bound to oxygen in the ZnO. − The Zn 2p 3/2 and 2p 1/2 peaks are at 1022.09 and 1045.8 eV, respectively (Figure S3c). For the InP/ZnO core/shell QDs, the In 3d peak shifts to higher binding energies located at 444.7 eV (3d 5/2 ) and 452.5 eV (3d 3/2 ), compared to the InP core QD (Figure S3a).…”