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Solution Processed High Efficiency Thin Film Solar Cells: from Copper Indium Chalcogenides to Methylammonium Lead Halides

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2016, Doctor of Philosophy, University of Toledo, Physics.
Photovoltaics (PV) is increasingly recognized as an important component of renewable energy sources after the rapid progress in the last decade due to increasing energy demand and reducing manufacturing costs. Despite the enormous growth of the PV market, the present solar technologies that are dominated by crystalline silicon are still limited by the relatively more expensive cost of electricity compared with power generation in the conventional fossil fuel plants. Consequently, there is an urgent need to increase the performance and reduce the manufacturing costs of solar cells. While the commercial thin film solar cells (CdTe and CuInGaSe2) have already demonstrated high efficiencies, the current fabrication processes heavily rely on intensive capital investment on expensive vacuum-based techniques. To reduce solar module costs, solution-processing techniques have been proposed as a promising route towards low cost, high throughput, large scale manufacturing of high efficiency thin film solar cells. In this thesis, we investigate the solution-processing of copper indium chalcogenides and methylammonium lead halides materials and their applications as high efficiency photovoltaic cells. In the first approach, we develop an ultrasonic spray deposition system to prepare the CuIn(S,Se)2 thin films. Spray deposition is a controllable, scalable, and high throughput process that is suitable for industrial manufacturing. Here we first explore the Cu-In-S films prepared by an aqueous precursor ink. By controlling the precursor composition, we fabricate PV devices consisting of the n-type In2S3 window and p-type CuInS2 absorber layers and demonstrate 2% efficiency in the preliminary devices. After replacing the aqueous ink by a hydrazine-based precursor solution and incorporating a selenization process, we are able to fabricate high quality CuIn(S,Se)2 thin film solar cells in both conventional substrate and the backwall superstrate configurations. The efficiency of 7.2% has been achieved in the sprayed CuIn(S,Se)2 devices in the substrate configuration. In the second approach, we investigate solution-processing of the inorganic-organic hybrid metal halide perovskites. We study the impact of reaction temperature and precursor composition on the formation of perovskite materials and propose a pseudo binary phase diagram to guide the processing of the materials. We develop a laser beam induced current (LBIC) technique to spatially resolve the photocurrent collection in the solution-processed devices. Processing defects and impurities phases have been identified as the origins of lower current generation. On the basis of these results, we apply advanced processing techniques in device processing and obtain the champion perovskite device with a 16% efficiency. Additionally, we image the photocurrent generated in the sub-cells of the Si/perovskite tandem devices. The result can be used to improve the design the device structure. Finally, to study the stability of perovskite solar cells, we investigate the spatial and temporal evolution of photocurrent collection across the devices and observe the partially reversible phase transition of perovskite in humid air.
Michael J. Heben, Ph.D. (Committee Chair)
Robert W. Collins, Ph.D. (Committee Member)
Randy J. Ellingson, Ph.D. (Committee Member)
Terry P. Bigioni, Ph.D. (Committee Member)
Lawrence S. Anderson-Huang, Ph.D. (Committee Member)
225 p.

Recommended Citations

Citations

  • Song, Z. (2016). Solution Processed High Efficiency Thin Film Solar Cells: from Copper Indium Chalcogenides to Methylammonium Lead Halides [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1470403462

    APA Style (7th edition)

  • Song, Zhaoning. Solution Processed High Efficiency Thin Film Solar Cells: from Copper Indium Chalcogenides to Methylammonium Lead Halides. 2016. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1470403462.

    MLA Style (8th edition)

  • Song, Zhaoning. "Solution Processed High Efficiency Thin Film Solar Cells: from Copper Indium Chalcogenides to Methylammonium Lead Halides." Doctoral dissertation, University of Toledo, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1470403462

    Chicago Manual of Style (17th edition)