Solid-state dye-sensitized solar cells based on spirofluorene (spiro-OMeTAD) and arylamines as hole transporting materials

Dye-sensitized solar cells are a promising solar technology because of their low cost, reliability, and high efficiency, compared with silicon-based solar cells. Efforts over the last two decades have increased solar cell efficiency to 12% based on liquid electrolytes, and more research on solid-state devices is necessary to determine their practical usage and long-term stability. The development of solid-state devices has achieved an overall efficiency over 7% using hole transporting materials. This study reviews current progress on hole transporting materials, sensitizers, and mesoporous TiO2 in solid-state dye-sensitized solar cells using small organic molecules as the hole transporting material. This study also discusses the key factors, such as molecular structure design and interfacial problems, affecting device performance.