Recharging upconversion: revealing rubrene's replacement

Abstract

One of the major limitations of solid-state perovskite-sensitized photon upconversion to date is that the only annihilator successfully paired with the perovskite sensitizer has been rubrene, raising the question of...

Generating spin-triplet states at the bulk perovskite/organic interface for photon upconversion

“…4d), highlights the rapid emergence of the triplet-related excited state absorption (ESA) features for the respective OSCs. 60 Additionally, evidence of SF within both OSCs can be observed under direct excitation under 400 nm (Fig. 4c and d).…”

“…Intermolecular coupling effects can already be observed in the two annihilators (rubrene and 1-CBPEA) discussed here. In the solid state, intermolecular interactions enable both SF and TTA, 60 and 1-CBPEA exhibits a significantly redshifted absorption feature caused by aggregation, and significantly redshifted emission. Considering that Schmidt and co-workers have demonstrated that excimer formation can be used to reduce the effects of SF, 70 and fabrication methods can tailor crystal arrangements as shown by Wasielewski and co-workers, which directly influence the intermolecular coupling in bis(phenylethynyl)anthracene (BPEA) and result in a change in the rate of SF, 167 these observations indicate that intermolecular couplings can be utilized to engineer the singlet and triplet energy surfaces to facilitate TTA-UC while suppressing unwanted relaxation pathways.…”

“…τ Rub > 10 μs). 60 Hence, all TTA-UC observed is expected to occur in a shorter time frame close to the interface.…”

“…1b alongside the two annihilators reported to date: RubDBP and 1-chloro-9,10-(bisphenylethynyl)anthracene (1-CBPEA). 60 The true potential of perovskite-sensitized TTA-UC will be accomplished once 800 nm (1.55 eV) incident light is successfully upconverted to ∼410 nm (3 eV), thus, maximizing the attainable energy gain obtained in the UC process.…”

“…2. 60 In the following minireview, we will detail the current understanding of the triplet generation mechanism at the perovskite/OSC interface and the resulting implications for photon UC and discuss the current status of the field of perovskite-sensitized TTA-UC. While significant advancements have been made in the fundamental understanding of the charge transfer processes underpinning perovskite-sensitized UC devices over the last few years and device improvements have made by compositional tuning and surface treatments, a key goal moving forward must be to both improve both the UC performance and the apparent anti-Stokes shift.…”