This lecture covers the principles and applications of dye-sensitized solar cells (DSSCs). It explains the operation of DSSCs, focusing on the kinetic competition between various electron transfer processes. The lecture discusses the mesoporous TiO2 photoanode, bulk heterojunctions, and the prevention of carrier recombination. It also explores the efficiency, stability, and energy conversion yield of DSSCs compared to traditional semiconductor devices. Additionally, it delves into the development of photosensitizers with high open-circuit photovoltage to enhance power conversion efficiency. The lecture concludes with a discussion on the dynamics of interfacial and surface electron transfer processes in DSSCs.