Sulfidation of electrodeposited microcrystalline/nanocrystalline cuprous oxide thin films for solar energy applications

Abstract

Grain size of polycrystalline semiconductor thin films in solar cells is optimized to enhance the efficiency of solar cells. This paper reports results on an investigation carried out on electrodeposited n-type cuprous oxide (Cu 2 O) thin films on Ti substrates with small crystallites and sulfidation of them to produce a thin-film solar cell. During electrodeposition of Cu 2 O films, pH of an aqueous acetate bath was optimized to obtain films of grain size of about 100 nm, that were then used as templates to grow thicker n-type nanocrystalline Cu 2 O films. XRD and SEM analysis revealed that the films were of single phase and the substrates were well covered by the films. A junction of Cu 2 O/Cu x S was formed by partially sulfiding the Cu 2 O films using an aqueous sodium sulfide solution. It was observed that the photovoltaic properties of nano Cu 2 O/Cu x S heterojunction structures are better than micro Cu 2 O/Cu x S heterojunction solar cells. Resulting Ti/nano Cu 2 O/Cu x S/Au solar cell structure produced an energy conversion efficiency of 0.54%, V oc = 610 mV and J sc = 3.4 mA cm −2 , under AM 1.5 illumination. This is a significant improvement compared to the use of microcrystalline thin film Cu 2 O in the solar cell structure where the efficiency of the cell was limited to 0.11%. This improvement is attributed mainly to the increased film surface area associated with nanocrystalline Cu 2 O films.

Effect of Bath pH on Interfacial Properties of Electrodeposited n‐Cu2O Films

“…Previously reported enhancements of photoresponse of various devices made with surface modified Cu 2 O with S 2− ions, could have been resulted due to the change in relative band edge position of electrodeposited Cu 2 O films at the interfaces, in addition to other contributions …”

Electrodeposited n‐type cuprous oxide cubic nanostructures for liquefied petroleum gas sensing

“…Cuprous oxide (Cu 2 O) is a well‐known metal oxide semiconductor with a direct band gap of ∼2.0 eV and having a cubic crystal structure with a lattice parameter of 4.27 Å. Cu 2 O is considered as an earth abundant, green material having a great potential to be used in many applications such as photovoltaics , gas sensing , electro‐catalysis , and photocatalysis . Due to the presence of Cu vacancies in the crystal lattice, Cu 2 O has been generally known as a p ‐type semiconductor .…”

“…Therefore, for optimal sensor performance, careful optimization of surface morphology (both size and shape) and stability of fabricated material over time are important. Electrochemical deposition has been used previously to fabricate nanostructured Cu 2 O thin films and has been utilized for photovoltaic applications . Among the many sensing applications of Cu 2 O (see Table for a summary), microcrystalline p ‐type Cu 2 O thin films fabricated using chemical bath deposition have been used for sensing of Methane and NO 2 gases , while Cu/Cu 2 O nano‐crystalline hollow spheres synthesized using a micro‐wave assisted hydrothermal method has shown the ability to detect NO 2 at room temperature .…”

“…Initially, a template was fabricated by electrodepositing p ‐type Cu 2 O on a Ti substrate in an acetate bath followed by annealing to change the conductivity. These films having nano‐cubic morphology were subsequently used to grow thicker n ‐type Cu 2 O films while preserving the surface morphology, a fabrication route previously demonstrated by Jayathilaka et al to increase the photovoltaic efficiency of Ti / nano Cu 2 O / Cu x S / Au cell structures.…”

Surfactant free template assisted electrodeposited n-type nano-cubic Cu2O thin films for nonenzymatic glucose sensing

“…The objective of this study is to show the enhancement in sensing performances for amperometric measurements in the presence of glucose when surface morphology is changed from micro to nanoscale by fabricating n-type Cu 2 O thin films with cubic nanostructures. Fabrication of the films was done by electrochemical deposition using a template-assisted surfactant free fabrication method [1]. Despite the simplicity of the fabrication method that involves only morphological manipulation of a single material (Cu 2 O), the linear range results obtained for glucose sensing can be rated as very high compared to the values reported in literature.…”