The development of clean alternatives to current power generation methods is immensely valuable for sustainable development (SD) in the global economy and environment. Photovoltaic devices offer an ideal solution by converting clean solar energy directly to electricity. Despite their high efficiency, however, silicon-based photovoltaic devices are precluded due to their high production cost and uncompetitive yields compared with conventional methods. Therefore, exploring non-silicon alternatives has gained significant momentum in both academia and industry during the past two decades with improved cost-effectiveness, applicability and sustainability. Promising photovoltaic systems such as all-polymer, small-molecule, poly/inorganic-nanoparticle hybrid, and dye-sensitized solar cells (DSSCs), have been rigorously investigated. In recent years, there has been growing interest in DSSCs, due to their low-cost, simple system fabrication and excellent efficiencies. One of the challenges of this technology is, however, the expensive and scarce novel metal (platinum or its alloys) typically used as electrocatalytic materials in the cells, inhibiting the practical application of DSSCs. In addition, there may be limited room for improvement in the counter electrode active materials to increase DSSCs performance. Atomic introduction of alien element (doping) to locally manipulate the surface structure of low-cost, earth abundant materials to unload or enhance their electrocatalytic performance has been acknowledged as an effective solution, however, the current doping approaches adopt bottom-up strategies leading to limited surface dopant levels. To address these problems, this thesis systematically explores an effective, generic, in-situ vapor-phase hydrothermal (VPH) doping approach for the fabrication of cost-effective, high-performance and chemically stable materials as the electrocatalyst materials on counter electrodes in DSSCs.