Nearly lattice matched all wurtzite CdSe/ZnTe type II core–shell nanowires with epitaxial interfaces for photovoltaics

Abstract

Achieving a high-quality interface is of great importance in core-shell nanowire solar cells, as it significantly inhibits interfacial recombination and thus improves the photovoltaic performance. Combining thermal evaporation of CdSe and pulsed laser deposition of ZnTe, we successfully synthesized nearly lattice matched all wurtzite CdSe/ZnTe core-shell nanowires on silicon substrates. Comprehensive morphological and structural characterizations revealed that a wurtzite ZnTe shell layer epitaxially grows over a wurtzite CdSe core nanowire with an abrupt interface. Further optical studies confirmed a high-quality interface and demonstrated efficient charge separation induced by the type-II band alignment. A representative photovoltaic device has been demonstrated and yielded an energy-conversion efficiency of 1.7% which can be further improved by surface passivation. The all-wurtzite core-shell nanowire with an epitaxial interface offers an attractive platform to explore the piezo-phototronic effect and promises an efficient hybrid nano-sized, energy harvesting system.

Enhanced Broad Band Photodetection through Piezo‐Phototronic Effect in CdSe/ZnTe Core/Shell Nanowire Array

“…[23][24][25] Previous reports on CdSe nanowire arrays also demonstrated its application in mechanical-to-electrical energy conversion, [ 26 ] and the piezo-phototronic effect was observed in a single CdSe nanowire device. [ 27 ] A more recent study, using a single CdSe/ ZnTe core/shell nanowire as a photovoltaic device, [ 28 ] shows that a ZnTe shell can be epitaxially grown on CdSe nanowire, which was attributed to their small lattice mismatch, similar thermal expansion coeffi cient and type-II band alignment. The wileyonlinelibrary.com promising optical performance from a CdSe/ZnTe core/shell nanowire, as well as, the piezoelectric effect in the CdSe core makes the core/shell architecture an excellent candidate for a piezo-phototronic device.…”

Progress in piezo-phototronic effect enhanced photodetectors

“…Both the ZnO/ZnS and CdSe/ZnTe core-shell nanowires which have type II alignment exhibit an efficient broad band UV/visible photoresponse. 132,133 The piezoelectric effect of ZnO and CdSe makes the two types of core-shell structures excellent candidates for piezo-phototronic effect devices. Fig.…”

Light-Effect Transistor (LET) with Multiple Independent Gating Controls for Optical Logic Gates and Optical Amplification

“…CdSe nanowires were grown in a vertical array through goldcatalyzed chemical vapor deposition, as described elsewhere, [27] and were then dispersed in alcohol and drop cast onto a Si/SiO 2 chip, which consists of Si substrate coated with a 300-nm thick SiO 2 layer. After CdSe nanowires were dispersed onto a chip, a thin poly-methyl methacrylate (PMMA) layer was spin coated onto the chip, followed by electron-beam lithography to open channels at a nanowire's ends.…”

“…In this work, we employ readily available CdSe SNWs [27,28] to demonstrate the LET concept and functions. We first characterize the material and devices, and then explore singlebeam optical gating effects with different wavelengths and laser powers (P g (λ g )), manifested in both output characteristic (I ds − V ds ) and transfer characteristic (I ds − P g ).…”