Up‐Conversion Photoluminescence in Polyfluorene Doped with Metal(II)–Octaethyl Porphyrins

Abstract

The up‐conversion photoluminescence (PL) in films of polyfluorene (PF) doped with metallated porphyrins is reported for the first time. The dependence of the up‐conversion process on the pump laser intensity and wavelength, the central metal moiety of the dopants, and the temperature is presented. Up‐conversion emission is observed at pump intensities as low as 2 kW cm–2. Comparison of the PF integral PL intensities after laser excitation by 532, 543, and 405 nm enables the discussion of the energy‐transfer mechanism and the efficiency of the process.

Visible‐Light Harvesting with Cyclometalated Iridium(III) Complexes Having Long‐Lived 3IL Excited States and Their Application in Triplet–Triplet‐Annihilation Based Upconversion

“…[21] Upconversion (UC) is important for photovoltaics, photocatalysis, and nonlinear photonics. [24,31,32] Among UC applications, such as two-photon absorption dyes, nonlinear optical crystals, or rare earth metal materials, [33] TTA upconversion is particularly interesting, because of its low excitation power (can be lower than the energy of solar light) and its readily adjustable excitation/emission wavelengths. [21][22][23][24] However, we note the limitations facing the current development of TTA upconversion, such as the limited availability of triplet sensitizers, which are currently limited to Ru II polyimine complexes [34] and Pt II /Pd II porphyrin complexes.…”

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

“…58 A strategy that might help to overcome part of this problem is the use of a polymer host which, at the same time, acts as the TTA emitter species, and is doped with only one triplet sensitizing species. Several groups have investigated these materials, including porphyrin-doped polyfluorene 59 , porphyrindoped poly-pentaphenylene 60 and porphyrin-doped superyellow. 32 Again, in most cases the aggregation of the porphyrin triplet sensitizers appeared to be a major problem.…”

Blue‐Green Up‐Conversion: Noncoherent Excitation by NIR Light

“…The process of photon up-conversion, based on triplettriplet annihilation in multimolecular systems, [5][6][7][8] is to be considered as an inherently connected chain of three processes already studied in the past. The first process in this chain is intersystem crossing (ISC), which is strongly enhanced by the spin-orbit coupling to the metal center of metalated macrocyclic sensitizer molecules.…”