Colloidal quantum dot solar cells exploiting hierarchical structuring

André J. Labelle, Susanna Thon, Silvia Masala, Michael M. Adachi, Haopeng Dong, Maryam Farahani, Alexander H. Ip, Andrea Fratalocchi, E. H. Sargent

Research output: Contribution to journalArticlepeer-review

120 Scopus citations

Abstract

Extremely thin-absorber solar cells offer low materials utilization and simplified manufacture but require improved means to enhance photon absorption in the active layer. Here, we report enhanced-absorption colloidal quantum dot (CQD) solar cells that feature transfer-stamped solution-processed pyramid-shaped electrodes employed in a hierarchically structured device. The pyramids increase, by up to a factor of 2, the external quantum efficiency of the device at absorption-limited wavelengths near the absorber band edge. We show that absorption enhancement can be optimized with increased pyramid angle with an appreciable net improvement in power conversion efficiency, that is, with the gain in current associated with improved absorption and extraction overcoming the smaller fractional decrease in open-circuit voltage associated with increased junction area. We show that the hierarchical combination of micron-scale structured electrodes with nanoscale films provides for an optimized enhancement at absorption-limited wavelengths. We fabricate 54.7° pyramid-patterned electrodes, conformally apply the quantum dot films, and report pyramid CQD solar cells that exhibit a 24% improvement in overall short-circuit current density with champion devices providing a power conversion efficiency of 9.2%.
Original languageEnglish (US)
Pages (from-to)1101-1108
Number of pages8
JournalNano Letters
Volume15
Issue number2
DOIs
StatePublished - Jan 9 2015

ASJC Scopus subject areas

  • Bioengineering
  • Materials Science(all)
  • Chemistry(all)
  • Mechanical Engineering
  • Condensed Matter Physics

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