Indexed on: 20 Sep '18Published on: 20 Sep '18Published in: Journal of Physical Chemistry Letters
Molecular photon upconversion via triplet-triplet annihilation (TTA-UC) is an intriguing strategy to increase solar cell efficiencies and surpass the Shockley-Quiesser (SQ) limit. In this perspective we recount our groups efforts to harness TTA-UC by directly incorporating metal ion linked multilayers of acceptor and sensitizer molecules into an organic-inorganic hybrid solar cell architecture. These self-assembled multilayers facilitate both upconverted emission and photocurrent generation from the upconverted state with a record contribution of 0.158 mA cm-2 under one sun solar flux. Here we recount the progression towards this record, the mechanistic insights learned along the way, summarize the rate/efficiency limiting events, as well as outline improvements that must be made to produce a viable TTA-UC solar cell that can pass the SQ limit. We also discuss the potential impact that efficient TTA-UC and photocurrent generation could have on existing record solar cells.