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

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 V_oc = 0.69 V and J_sc = 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.