Indium tin oxide as a semiconductor material in efficient p-type dye-sensitized solar cells

Ze Yu,Udo Bach,Jacek J Jasieniak,Torben Daeneke,Peter Bäuerle,Amaresh Mishra,Ishanie R Perera,Yasuhiro Tachibana,Satoshi Makuta,Leone Spiccia

doi:10.1038/am.2016.89

Abstract

Indium tin oxide (ITO) is a well-known n-type degenerate semiconductor. Herein, mesoporous ITO is utilized as a photocathode material for p-type dye-sensitized solar cells in place of the commonly applied p-type semiconductors, such as nickel oxide. In conjunction with [Fe(acac)3]0/− as redox mediator and a new sensitizer, an impressive energy conversion efficiency of 1.96±0.12% was achieved. Photoelectron spectroscopy in air revealed that ITO exhibits a significant local density of states arising below −4.8 eV, which enables electron transfer to occur from ITO to the excited dye, giving rise to the sustained photocathodic current.

Highlights

Transparent conducting oxides have been extensively used in optoelectronic applications.[1,2,3] One common transparent conducting oxide is indium tin oxide (ITO)
The oligothiophene spacer group was shown to have a vital role in suppressing charge recombination between holes in the nickel oxide (NiO) valence band and the photoreduced state of the dye formed by photoinduced hole injection.[25]
Semiconductor films with optimized thicknesses of 3.5 μm (ITO) and 3.1 μm (NiO) were used to assemble all p-dye-sensitized solar cell (DSC) reported in this study (Supplementary Figures S1 and S2)

Summary

Introduction

Transparent conducting oxides have been extensively used in optoelectronic applications.[1,2,3] One common transparent conducting oxide is indium tin oxide (ITO). ITO is a well-known n-type degenerate semiconductor[4] with an optical band gap of 3.5–4.3 eV5 and has a high transmission in the near infrared and visible regions of the electromagnetic spectrum. Owing to their high optical transparency, good electrical conductivity, chemical inertness, hardness and excellent substrate adherence,[6,7,8] ITO thin films are applied in flat panel displays, antistatic coatings, solar cells, camera lenses and architectural glazing.[9,10,11,12] high-surface-area mesoporous ITO films have been used as sensors for gases, such as ammonia, nitric oxide, ethanol and methanol.[13,14,15,16] ITO films and ITO/TiO2 core-shell structures have been utilized as photoanodes in both dye-sensitized solar cells (DSCs) and water oxidation devices.[17,18,19,20]

Methods

Results

Conclusion