Novel nanoparticle synthesis and nano-ink film for photovoltaic applications
Abstract
Thin film solar cells have been spotlighted and extensively studied as one of the most promising energy sources due to its cost efficiency and sustainability. Even though CdTe or CIGS has drawn considerable attention, tellurium and indium are too rare in Earth’s crust to produce solar cells in commercial quantity, and even hazardous to the environment. Therefore, for the next generation of thin film solar cells, novel photovoltaic nanocrystals satisfying price competitiveness, stability, and safety requirement are necessary. Also, solution-based synthesis is more favored over sputtering deposition in the respect of the scalability and price. In this study, nanocrystalline semiconducting materials with group I-V-VI compounds with tunable composition are synthesized using copper and antimony precursors and sulfur source by multi-step hot injection method under air-free condition. The effects of synthetic procedures and post-synthesis on Cu/Sb and Cu/S stoichiometry and their nanocrystal structures are investigated and optimized by careful control of ligands and reaction preferences. Properties such as crystal structure, particle size and elemental composition of pure Cu3SbS4 and CuSbS2 are characterized by a series of spectroscopic techniques including XRD, SEM, TEM and Raman spectroscopy. Then, the nanocrystals synthesized are (i) deposited onto molybdenum substrates made by sputtering process, (ii) sintered by chemical vapor deposition (CVD), preventing impurities or decomposition where dense Cu3SbSe 4 or CuSbS2 thin films with sub-micron sized grains are formed upon selenization or sulfurization, (iii) fabricated to device by deposition of CdS/i-ZnO/ITO structure on sintered film and then finally (iv) characterized via various optical and electrical techniques to evaluate the suitability for potential applications to photo-absorbing layer. The resulting photovoltaic devices are used to examine how material properties of nanoparticles have influenced on device performance and show existing solution process for solar cells is adjustable to various semiconducting materials.
Degree
Ph.D.
Advisors
Agrawal, Purdue University.
Subject Area
Chemical engineering|Nanotechnology
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