Lifetime analysis of dye and perovskite solar cells

Armi Tiihonen

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

Dye solar cells (DSCs) and perovskite solar cells (PSCs) are promising future photovoltaics technologies. They demonstrate promise in terms of lower costs and mass-production and could thus help transform photovoltaics into a mainstream energy option. Many applications of photovoltaics, such as building integration, require a lifetime of decades to be economically sensible. This work focuses on understanding the aging mechanisms and extending the lifetime of DSCs and PSCs. In DSCs, the insufficient stability of the electrolyte component is a major weakness. Commonly applied liquid electrolytes are difficult to seal reliably into the cell. Thus, a method for sealing large-area cells utilizing nanocellulose aerogel membranes was developed in this work. The main stability challenge is the diminution of charge carriers in electrolyte (i.e., electrolyte bleaching) when the cells are exposed to environmental stress factors. In this work, purification of electrolyte solvent was observed to halve the progress of bleaching when the cells were exposed to ultraviolet light (UV). Also the application of a UV filter and the change of the redox couple from iodine to cobalt complex effectively suppressed the bleaching. Cobalt complex electrolytes have been regarded as unstable but here it was detected for the first time that the cobalt complex bleaches at a slower rate in comparison to the traditional iodine electrolyte. A perovskite precursor ink was developed in this work for printing carbon based PSCs. In this respect, all the material layers of the cell were manufactured accurately using upscalable methods. Perovskite decomposition under humidity or UV is a major aging mechanism. Here, the exceptionally stable PSCs prepared here were shown to withstand these stress factors in accelerated aging tests for one thousand hours. Also a photographing method was applied to explore perovskite decomposition. A survey of the state-of-the-art degradation studies of PSCs and DSCs revealed insufficient reporting and experimental procedures. Therefore, improved procedures were elaborated upon in this work, which also could contribute to improving the lifetime of DSSC and PSC solar cells.
Translated title of the contributionVäriaine- ja perovskiittiaurinkokennojen elinaikatutkimuksia
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Lund, Peter, Supervising Professor
  • Miettunen, Kati, Thesis Advisor
Publisher
Print ISBNs978-952-60-7879-3
Electronic ISBNs978-952-60-7880-9
Publication statusPublished - 2018
MoE publication typeG5 Doctoral dissertation (article)

Keywords

  • photovoltaics
  • dye solar cells
  • perovskite solar cells
  • stability
  • lifetime
  • aging tests
  • electrolyte

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