Solid-State Sensitized Upconversion in Polyacrylate Elastomers

Abstract

The sensitized triplet–triplet annihilation-based upconversion in bicomponent systems is currently considered the most promising strategy for increasing the light-harvesting ability of solar cells. Flexible, manageable, inexpensive up-converting devices become possible by implementing this process in elastomers. Here, we report a study combining optical spectroscopy data of the light conversion process with the nano- and macroscopic viscoelastic characterization of the host material embedding the active dyes, in order to find a rationale for the fabrication of efficient solid-state upconverting systems. By using the poly­(n-alkyl acrylates) as a model of the monophasic elastomers, we demonstrate that the yield of the bimolecular interactions at the base of the upconversion process, namely, energy transfer and triplet–triplet annihilation, is mainly determined by the glass transition temperature (T g) of the polymer. By employing the polyoctyl acrylate (T g = 211 K), we achieved a conversion yield at the solid state larger than 10% at an irradiance of 1 sun, showing the potential of the elastomer-based upconverting materials for developing real-world devices.

Time Domain NMR in Polymer Science: From the Laboratory to the Industry

“…To match the need for solid supports and a high diffusion path length to ease the probability for the active molecules to get in contact with each other, polymers are addressed as the most adequate matrixes. An interesting correlation has been found out between the active molecules decay rates and the T 2 of a series of polyacrylates [55]. For the sensitizer molecule, the local rigidity that characterizes the polyacrylates is not sufficient to suppress its decay rate, because of inelastic processes, while an increase of mobility, reflecting on an increase of 1 H T 2 , that happens in acrylates with long side chains, favors the decay rate of the emitter, increasing the overall efficiency of the device.…”

Towards Efficient Spectral Converters through Materials Design for Luminescent Solar Devices

“…also reported efficient TTA-UC in polyacrylate elastomers of different sidechain lengths doped with a platinum(II) octaetyl-porphyrin (PtOEP) and 9,10-diphenylanthracene (DPA) and sensitizer-emitter pair, with the UC efficiency being directly related to the diffusion length and T g of the elastomers. [163] Emissive conjugated poly(fluorenes) doped with metal(II) octaetyl porphyrins have also been investigated as dual host-emitter upconversion layers and show temperature dependent photoluminescence. [164] Some of the most promising recent results have been obtained with quasi-solid gels.…”

Nanodroplet‐Containing Polymers for Efficient Low‐Power Light Upconversion

“…This method has practical advantages over using a primary standard and is an accepted practice in the field. [28,55,57] The theoretical maximum UC quantum efficiency is 0.50, since the TTA-UC process uses two low energy photons to produce one high-energy photon. The maximum ΦUC of the secondary standard is 0.26, under excitation at 532 nm and a power density of 100 mW cm -2 ; it was measured and calculated by using the laser dye Rhodamine 6G (10 -5 M in ethanol) as reference material.…”