Dye-Sensitized Solar Cells Based on Nanocrystalline TiO2 Films Surface Treated with Al3+ Ions:  Photovoltage and Electron Transport Studies

• Published in: The journal of physical chemistry. B Vol. 109; no. 39; pp. 18483 - 18490
• Main Authors: Alarcón, H, Boschloo, G, Mendoza, P, Solis, J. L, Hagfeldt, A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06.10.2005
• Subjects: conversion; efficiency; light; oxide; recombination; thin-layer
• ISSN: 1520-6106; 1520-5207; 1520-5207
• DOI: 10.1021/jp0513521

Nanocrystalline TiO2 films, surface modified with Al3+, were manufactured by depositing a TiO2 suspension containing small amounts of aluminum nitrate or aluminum chloride onto conducting glass substrates, followed by drying, compression, and finally heating to 530 °C. Electrodes prepared with TiO2 nanoparticles coated with less than 0.3 wt % aluminum oxide with respect to TiO2 improved the efficiency of the dye sensitized solar cell. This amount corresponds to less than a monolayer of aluminum oxide. Thus, the Al ions terminate the TiO2 surface rather than form a distinct aluminum oxide layer. The aluminum ion surface treatment affects the solar cell in different ways:  the potential of the conduction band is shifted, the electron lifetime is increased, and the electron transport is slower when aluminum ions are present between interconnected TiO2 particles.