Photon upconversion facilitated molecular solar energy storage

Abstract

Photon upconversion is used to facilitate the production of a solar fuel. This is done by collocating a triplet-triplet annihilation upconversion system in a microfluidic device with a molecular solar thermal energy storage system. Incoherent truncated white light is used to drive the reaction and the green part of the spectrum is upconverted to blue light, which in turn is absorbed by the solar fuel.

Photochemical upconversion: present status and prospects for its application to solar energy conversion

“…17,20 TTA-upconversion is an incoherent process, and the intrinsic intermediate energy storage in the triplet states allows for its efficient operation under low-light conditions. There are examples of lanthanoid upconversion proceeding efficiently under broadband, pulsed supercontinuum radiation, 21,22 but several studies have shown TTA-upconversion under broadband white-light illumination, 23,24 with some demonstrations even employing sunlight itself as the excitation source. 25,26 2.1.2 Components of a TTA-UC system.…”

“…The liquid molecular solar thermal (MOST) storage medium and the liquid TTA system, both dissolved in toluene, were cycled through a microfluidic chip as the light-harvesting surface. 23 TTA-UC was further employed to sensitize photochemical reactions for other applications: Islangulov et al sensitized TTA between anthracene with the metal-to-ligand chargetransfer (MLCT) sensitizer [Ru(dmb) 3 ] in order to produce reactive excited singlet species prone to cycloaddition chemistry, resulting in the formation of anthracene dimers. 130 Jiang et al used a red-absorbing porphyrin/anthracene-derivative TTA couple to sensitize trans-cis-photoisomerization of azotolane in a cross-linked liquid-crystal polymer, resulting in a photomechanical effect with potential application in soft actuation.…”

Triplet–triplet annihilation upconversion from rationally designed polymeric emitters with tunable inter-chromophore distances

“…[3] Enhancement of solar fuel production of ~130% using a TTA-UC system has been reported in a recent study. [4] The TTA-UC process is a sequence of events: a sensitizer becomes excited and reaches a triplet state via intersystem crossing (ISC); triplet-triplet energy transfer (TTET) between 35 sensitizer and emitter; triplet-triplet annihilation (TTA) between two emitters leading to a singlet excited state of one of them; and the final upconverted emission from the singlet excited acceptor ( Figure S6 in the Supporting Information). [5][6][7] The TTET and TTA steps in the sequence require collisions between two triplets.…”

Recent advances in the application triplet–triplet annihilation-based photon upconversion systems to solar technologies

“…By further developing this approach, we recently obtained the record enhancement of photocurrent generated in a standard PCWS cell under solar irradiance exploiting a sTTA-UC polymer boosted with highly fluorescent semiconductor nanocrystals, thus showing how the sTTA-UC materials can be successfully implemented in technologically relevant devices while matching the strict requirements of clean-energy production. 72 Börjesson et al 73 reported another example of a photochemical reaction enhanced by sTTA-UC, where the photoisomerization of a fulvalene diruthenium derivative (FvRu 2 ) was driven by blue photons upconverted from truncated white light. In the study, they set up a microfluidic system (Fig.…”