Type-II Core/Shell Nanowire Heterostructures and Their Photovoltaic Applications

Abstract

Nanowire-based photovoltaic devices have the advantages over planar devices in light absorption and charge transport and collection. Recently, a new strategy relying on type-II band alignment has been proposed to facilitate efficient charge separation in core/shell nanowire solar cells. This paper reviews the type-II heterojunction solar cells based on core/shell nanowire arrays, and specifically focuses on the progress of theoretical design and fabrication of type-II ZnO/ZnSe core/shell nanowire-based solar cells. A strong photoresponse associated with the type-II interfacial transition exhibits a threshold of 1.6 eV, which demonstrates the feasibility and great potential for exploring all-inorganic versions of type-II heterojunction solar cells using wide bandgap semiconductors. Future prospects in this area are also outlooked.

A Review of Direct Z‐Scheme Photocatalysts

“…Specifically, a typical direct Z‐scheme system has a charge‐carrier migration pathway that resembles the letter “Z” (Figure b) . During the photocatalytic reaction, the photogenerated electrons in semiconductor B, with lower reduction ability, recombine with the photogenerated holes in semiconductor A with a lower oxidation ability (Figure b) . Therefore, the photogenerated electrons in semiconductor A with high reduction ability and photogenerated holes in semiconductor B with a high oxidation ability can be maintained.…”

Efficient charge separation based on type-II g-C3N4/TiO2-B nanowire/tube heterostructure photocatalysts

“…This situation could be worsened when internal modifications such as doping are applied in order to ameliorate their optical properties 15 . However, charge recombination can be significantly suppressed when type II band alignment is formed among different semiconductors [16][17][18][19] . Efficient electron-hole separation and enhanced quantum efficiency has been found in a wealth of systems including TiO 2 /CdS/CuInS 2 20 , Ag x Zn 1-x O/ZnO 21 , InVO 4 /TiO 2 22 , ZnS/SnO 2 23 , p-BiOI/n-SnS 2 24 etc., of which g-C 3 N 4 has been widely considered as an ideal semiconductor for the fabrication of heterostructures with various semiconductors for the following reasons: (1) a small band gap (~2.75 eV) that enables visible light absorption; (2) a highly negative location of conduction band (CB) minimum (-1.12 eV vs. NHE) that facilitate electron transferring to the other semiconductors; (3) cheap and simple synthetic routes that secure large scale production and modifications [25][26][27][28][29] .…”

Facile synthesis of composition-tuned ZnO/Zn x Cd1-x Se nanowires for photovoltaic applications

“…One-dimensional nanostructures have attracted considerable attention due to their unique advantages and potential applications in photovoltaic devices [1-3]. In particular, nanostructured oxide semiconductors, such as ZnO nanowires (NWs) and TiO 2 nanocrystals, have been widely applied to photo-electrochemical (PEC) cells or solar cells owing to the low cost and high stability against photocorrosion, and mature fabrication techniques [4-13].…”