Intrinsic burn-in efficiency loss of small-molecule organic photovoltaic cells due to exciton-induced trap formation

Xiaoran Tong, Nana Wang, Michael Slootsky, Junsheng Yu, Stephen R. Forrest

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

The intrinsic degradation mechanisms leading to the initial burn-in deterioration in power conversion efficiency in small-molecule-based organic photovoltaics (OPVs) are studied. Specifically, we examine degradation in archetype boron subphthalocyanine chloride/fullerene OPVs in the absence of atmospheric contaminants such as water and oxygen. During the initial burn-in period (<20 h), planar OPVs employing C60 as the acceptor exhibits a rapid decrease in efficiency that is primarily due to a reduction in photocurrent contributed by excitons generated in C60, as observed by the changes in the spectrally-resolved external quantum efficiency. We develop an analytical model that ascribes the decrease in power conversion efficiency with aging to an energetically-driven increase in the density of exciton-induced quenching sites that hinder exciton diffusion to the donor-acceptor interface. This mechanism is mitigated by employing a C70 acceptor, or a mixed donor-acceptor active layer where excitons are rapidly dissociated following photogeneration, thereby significantly reducing their lifetime and density.

Original languageEnglish
Pages (from-to)116-123
Number of pages8
JournalSolar Energy Materials and Solar Cells
Volume118
DOIs
StatePublished - 2013
Externally publishedYes

Keywords

  • Aging
  • Lifetime
  • Reliability
  • Small molecule

Fingerprint

Dive into the research topics of 'Intrinsic burn-in efficiency loss of small-molecule organic photovoltaic cells due to exciton-induced trap formation'. Together they form a unique fingerprint.

Cite this