Melt-processed polymer glasses for low-power upconversion via sensitized triplet–triplet annihilation

Abstract

The process of low-power light upconversion by triplet–triplet annihilation is well established in solutions of appropriate sensitizer–emitter pairs, but has only recently been reduced to practice in polymeric materials. Here, the fabrication of upconverting glasses based on poly(methyl methacrylate) (PMMA), palladium octaethylporphyrin (PdOEP, sensitizer, 0.005–0.5% w/w relative to the polymer) and large amounts of diphenylanthracene (DPA, emitter, 25% w/w relative to the polymer) is reported. These materials were produced by compression-molding pre-mixed blends and subsequently quenching the samples in a molecularly mixed state. The resulting films upconvert green incident light (543 nm) of low incident power density (34 mW cm⁻²) into blue light (440 nm). The dependence of the upconversion intensity on the sensitizer concentration was studied and the results suggest that an optimal composition range exists, where the upconversion efficiency is maximal.