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Efficiency of bulk perovskite-sensitized upconversion: Illuminating matters

Authors :
Jens Lackner
Sarah Wieghold
Zachary A. VanOrman
G. Ulrich Nienhaus
Karin Nienhaus
Lea Nienhaus
Source :
Applied Physics Letters. 118:203903
Publication Year :
2021
Publisher :
AIP Publishing, 2021.

Abstract

Photon upconversion via triplet–triplet annihilation could allow for the existing efficiency limit of single junction solar cells to be surpassed. Indeed, efficient upconversion at subsolar fluences has been realized in bulk perovskite-sensitized systems. Many questions have remained unanswered, in particular, regarding their behavior under photovoltaic operating conditions. Here, we investigate the impact of repeated and continuous illumination on bilayer perovskite/rubrene upconversion devices. We find that variations of the underlying perovskite carrier recombination dynamics greatly impact the upconversion process. Trap filling and triplet sensitization are in direct competition: more saturated trap states in the perovskite and, thus, longer underlying perovskite photoluminescence lifetimes allow for an increased number of carriers to diffuse to the perovskite/rubrene interface and undergo charge extraction to the triplet state of rubrene. As a result, the upconversion efficiency is greatly influenced by the underlying trap density: the upconverted photoluminescence intensity increases by two orders of magnitude under continuous illumination for 4 h. This shows that the upconversion efficiency is difficult to define for this system. Importantly, these results indicate that perovskite-sensitized upconversion devices exhibit peak performance under continuous illumination, which is a requirement for their successful integration into photovoltaics to help overcome the Shockley–Queisser limit in single junction solar cells.

Details

ISSN :
10773118 and 00036951
Volume :
118
Database :
OpenAIRE
Journal :
Applied Physics Letters
Accession number :
edsair.doi...........0c4f4dd85ba42ccd976f8b24379b2dc3
Full Text :
https://doi.org/10.1063/5.0050185