Interfacial engineering of quantum dot-sensitized TiO2 fibrous electrodes for futuristic photoanodes in photovoltaic applications

Abstract

Herein we report generic surface treatment approaches to improve the electronic interfaces of quantum dot-sensitized TiO2 fiber electrodes, thereby promoting their photoanode performance. Highly dense, continuous and nanostructured TiO2 fibrous membranes, without the inclusion of a scattering layer, unlike conventional TiO2 particulate electrodes, showed feasible photoconversion performance under the proposed interfacial engineering modification. The proposed interfacial treatment concerns fibrous membranes both before and after calcination. The chemical vapor pre-treatment on an as-deposited fibrous membrane using tetrahydrofuran (THF) reinforces the physical contact between the fibrous membrane and the transparent conducting substrate and reduces significantly the recombination rate. In the case of post-treatment by F-ion on a fibrous surface, together with the interfacial engineering approach, the ZnS surface passivation layer markedly improves the photoanode performance of the TiO2 fibrous membrane nearly to a factor of 3.2% with a remarkable open-circuit voltage Voc 1⁄4 0.69 V and Jsc 1⁄4 13 mA cm␣2 under 1 sun illumination (100 mW cm␣2). This report provides an excellent platform for studying and understanding the interfacial contacts and mechanisms related to the charge transfer at CdS/CdSe QD-sensitized TiO2 fibrous assemblies. Such implications of this interfacial treatment strategy can be successfully extended to a wide range of photoanode candidates in energy conversion systems and confirm the effectiveness of some alternative nanostructured electrodes for the development of semiconductor-sensitized solar cells.