Polymer – nanocrystal tandem solar cells for enhanced power conversion efficiencies

Groeneveld, B.G.H.M. (2015) Polymer – nanocrystal tandem solar cells for enhanced power conversion efficiencies. Master's Thesis / Essay, Physics.

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Abstract

This thesis focuses on a novel type of solar cell: a series-connected tandem solar cell consisting of a polymer-fullerene blend subcell in combination with a subcell made of lead sulfide nanocrystals. These two classes of materials have been used extensively in photovoltaic research on single solar cells. The main advantages of using these solar cells are the low costs and ease of processing of the devices. However, the major challenge is that the efficiencies of these so-called thin film solar cells are relatively low, preventing them from competing with commercial silicon cells. The tandem structure makes it possible to use both materials in one device, which increases the maximum attainable efficiency greatly. In theory it is possible to exceed the efficiency of silicon cells with a tandem cell. It is necessary to optimize all the layers in the tandem structure before this can become reality. In practice, this means that the thicknesses of the layers need to be fine-tuned for optimal charge generation in the device. In addition to this, the energy levels of all materials have to be aligned in such a way that the generated charges can be extracted efficiently. A very important role is that of the interlayer, which has to act as a recombination site to prevent the build-up of charges in the device. However, the interlayer has to meet more requirements and proved to be a delicate element in the design and fabrication of tandem solar cells. The experiments on the optimization of several polymer-fullerene – lead sulfide tandem structures are described in this work. These led to the fabrication of a P3HT:PCBM – PbS tandem cell with 1.64% power conversion efficiency. This efficiency was higher than that of the polymer subcell, and identical to the PCE of the lead sulfide subcell, suggesting that the tandem structure is capable of enhancing the efficiency of single solar cells.

Item Type:	Thesis (Master's Thesis / Essay)
Degree programme:	Physics
Thesis type:	Master's Thesis / Essay
Language:	English
Date Deposited:	15 Feb 2018 08:03
Last Modified:	21 Sep 2023 06:44
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/12666

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