Low power upconversion using MLCT sensitizers

Abstract

Selective low energy excitation of the metal-to-ligand charge transfer (MLCT) transition in [Ru(dmb)(3)](2+)(dmb = 4,4'-dimethyl-2,2'-bipyridine) in the presence of anthracene or 9,10-diphenylanthracene yields easily visualized upconverted singlet fluorescence resulting from triplet-triplet annihilation at low excitation power.

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

“…[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. [21,24] It is very difficult for these complexes to be chemically modified to optimize their photophysical properties, such as excitation wavelength and lifetime and energy level of the T 1 state, etc (all these properties are important for TTA upconversion), for upconversion purposes.…”

Visible‐Light‐Harvesting Triphenylamine Ethynyl C60‐BODIPY Dyads as Heavy‐Atom‐Free Organic Triplet Photosensitizers for Triplet‐Triplet Annihilation Upconversion

“…For example, anthracene undergoes efficient ISC, but 9,10-diphenylanthracene has very weak ISC. [19,23] Therefore, it is highly desirable to develop a general molecular motif for organic triplet photosensitizers in which the molecular structure can be readily changed and the photophysical properties, such as UV/Vis absorption and solubility, can be easily optimized. More importantly, the ISC effect of the designed chromophore should be fully predictable.…”

The fragment spin difference scheme for triplet-triplet energy transfer coupling

“…[1][2][3][4] TET has become increasingly important recently since the triplet states provide a chance to design materials with interesting properties for potentially useful applications. [5][6][7][8][9][10] For example, the triplet light emission offers a chance of increasing the quantum yield in the statistics of charge recombination in electroluminescence. [11][12][13][14][15][16] The electronic coupling is one of the factors that determine excitation energy transfer rates.…”