Advanced Organic Hole Transport Materials for Solution-Processed Photovoltaic Devices

Abstract: Solution-processable photovoltaic devices (PVs), such as perovskite solar cells (PSCs) and solid-state dye-sensitized solar cells (sDSCs) show great potential to replace the conventional silicon-based solar cells for achieving low-cost and large-area solar electrical energy generation in the near future, due to their easy manufacture and high efficiency. Organic hole transport materials (HTMs) play important roles in both PSCs and sDSCs, and thereby can well facilitate the hole separation and transportation, for obtaining high performance solar cells.The studies in this thesis aimed to develop advanced small-molecule organic HTMs with low-cost, high hole mobility and conductivity for the achievement of highly efficient, stable and reproducible sDSCs and PSCs. In order to achieve these objectives, two different strategies were utilized in this thesis: the development of new generation HTMs with simple synthetic routes and the introduction of cost-effective p-type dopants to control the charge transport properties of HTMs.In Chapter 1 and Chapter 2, a general introduction of the solution-processed sDSCs and PSCs, as well as the characterization methods that are used in this thesis were presented.In Chapter 3 and Chapter 4, a series of novel triphenylamine- and carbazole- based HTMs with different oxidation potential, hole mobility, conductivity and molecular size were designed and synthesized, and then systematically applied and investigated in sDSCs and PSCs.In Chapter 5, two low-cost and colorless p-type dopants AgTFSI and TeCA were introduced for the organic HTM-Spiro-OMeTAD, which can significantly increase the conductivity of the Spiro-OMeTAD films. The doping effects on the influence of sDSC and PSC device performances were also systematically investigated.