Achieving spin-triplet exciton transfer between silicon and molecular acceptors for photon upconversion

Abstract

convert infrared light into the visible range are desirable as they can enable advanced schemes for photocatalysts 1 , solar energy harvesting 2 , deep tissue imaging 3 and phototherapy 4. Inorganic nanocrystals (NCs) functionalized with energy-accepting dyes form a promising platform to meet this demand. These materials achieve light upconversion by using photons absorbed by the NC to excite spin-triplet excitons centred on organic molecules tethered to their surface 5-7. Pairs of these excitons can merge through a process known as triplet fusion to produce high-energy spin-singlet states that emit visible light. Although upconversion efficiencies of >10% have been achieved by this approach 8,9 , these systems have exclusively employed NCs containing toxic heavy elements such as cadmium or lead (refs. 5,6,10), limiting their range of utility. Replacement of these NCs with nontoxic infrared absorbers is a key step in designing upconversion systems suitable for both biological and environmental applications.

Improved photon absorption in dye-functionalized silicon nanocrystals synthesizedviamicrowave-assisted hydrosilylation

“…43 Recently, Xia et al described triplet-triplet annihilation upconversion utilizing energy transfer from SiNc to the triplet sate of diphenylanthracene anchored with the SiNc surface. 44 To validate this idea, the PL decays of the SiNc emission ( Fig. 4a) were measured.…”

One‐Step Fabrication of Perovskite‐Based Upconversion Devices

“…A wide variety of materials classes for use as triplet sensitizers have been reported, ranging from metal-organic complexes with strong spin-orbit coupling, [4,19,20,22,[26][27][28][29][30][31] conventional semiconductor quantum dots (QDs)" [32][33][34][35][36][37][38][39][40] two-dimensional CdSe nanoplatelets, [41] perovskite-based QDs, [17,21,42,43] transition metal dichalcogenides, [44,45] two-dimensional perovskites [46] to bulk three-dimensional perovskites. [47][48][49][50][51] In the following, we will focus on the methylammonium formamidinium lead triiodide (MAFA) bulk perovskite sensitization of triplet states in the organic semiconductor rubrene by charge transfer.…”

Low-Dimensional Semiconductors in Artificial Photosynthesis: An Outlook for the Interactions between Particles/Quasiparticles

“…A prime example is by taking advantage of the TTA-based upconversion process in hybrid photocatalyst systems. 41 , 56 − 58 TTA enables high-lying (or hot) singlet excitons to be generated by the collisions between triplet excitons, and the utilization of high-lying singlet excitons before their cooling down would bring about rich possibilities for utilizing low-energy photons. For instance, we have proposed the utilization of ketones as molecular cocatalysts to promote the visible-light response of polymeric carbon nitride.…”