Colloidal semiconductor quantum dots (QDs) are attractive building blocks for solar photovoltaics (PV). In this talk, I will provide an overview our ongoing efforts to design lead salt QD thin film absorbers for next-generation PV. Basic requirements for QD absorber layers include efficient light absorption, charge separation, charge transport, and long-term stability. I will first discuss several methods used to make conductive QD films by solution deposition and ligand exchange. Studies of carrier mobility as a function of basic film parameters such as inter-QD spacing, QD size, and QD size distribution have led to a better understanding of charge transport within highly disordered QD films. Efforts to improve carrier mobility by enhancing inter-dot electronic coupling, passivating surface states, and implementing rudimentary doping will be highlighted. Engineering the inter-QD matrix to produce QD/inorganic or QD/organic nanocomposites is introduced as a promising way to optimize coupling, remove surface states, and achieve long-term environmental stability for high-performance, robust QD films. To obtain large photocurrent from QD solar cells, it is critical to increase the minority carrier diffusion length to rival the optical absorption length, possibly by harnessing band-like transport through extended electronic states. The relative roles of superlattice order, energy disorder, and surface states in this regard will be summarized. New results from in situ spectroscopic studies of QD field-effect transistors will be discussed.

Developing quantum dot solids for thin-film photovoltaics

247th National Meeting (2014)

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