“…This alleviates the commonly observed PL quenching which increases at longer emission wavelength, limiting the PL quantum efficiency of NIR emitters to 5–12%. [ 21 ] Therefore, improving the PLQY by reducing the non‐radiative decay channels of J‐aggregates is necessary to enhance the performance of the hybrid systems discussed above. [ 19,20,22–25 ] Furthermore, emitters with ultra‐narrow PL spectra are of great importance in active pixel display technologies, where the narrow‐emission band could result in emitting devices with more brilliant colors.…”
Supramolecular assemblies from organic dyes forming J‐aggregates are known to exhibit narrowband photoluminescence with full‐width at half maximum of ≈9 nm (260 cm−1). Applications of these high color purity emitters, however, are hampered by the rather low photoluminescence quantum yields reported for cyanine J‐aggregates, even when formed in solution. Here, it is demonstrated that cyanine J‐aggregates can reach an order of magnitude higher photoluminescence quantum yield (increase from 5% to 60%) in blend solutions of water and alkylamines at room temperature. By means of time‐resolved photoluminescence studies, an increase in the exciton lifetime as a result of the suppression of non‐radiative processes is shown. Small‐angle neutron scattering studies suggest a necessary condition for the formation of such highly emissive J‐aggregates: the presence of a sharp water/amine interface for J‐aggregate assembly and the coexistence of nanoscale‐sized water and amine domains to restrict the J‐aggregate size and solubilize monomers, respectively.
“…This alleviates the commonly observed PL quenching which increases at longer emission wavelength, limiting the PL quantum efficiency of NIR emitters to 5–12%. [ 21 ] Therefore, improving the PLQY by reducing the non‐radiative decay channels of J‐aggregates is necessary to enhance the performance of the hybrid systems discussed above. [ 19,20,22–25 ] Furthermore, emitters with ultra‐narrow PL spectra are of great importance in active pixel display technologies, where the narrow‐emission band could result in emitting devices with more brilliant colors.…”
Supramolecular assemblies from organic dyes forming J‐aggregates are known to exhibit narrowband photoluminescence with full‐width at half maximum of ≈9 nm (260 cm−1). Applications of these high color purity emitters, however, are hampered by the rather low photoluminescence quantum yields reported for cyanine J‐aggregates, even when formed in solution. Here, it is demonstrated that cyanine J‐aggregates can reach an order of magnitude higher photoluminescence quantum yield (increase from 5% to 60%) in blend solutions of water and alkylamines at room temperature. By means of time‐resolved photoluminescence studies, an increase in the exciton lifetime as a result of the suppression of non‐radiative processes is shown. Small‐angle neutron scattering studies suggest a necessary condition for the formation of such highly emissive J‐aggregates: the presence of a sharp water/amine interface for J‐aggregate assembly and the coexistence of nanoscale‐sized water and amine domains to restrict the J‐aggregate size and solubilize monomers, respectively.
“…Similarly, Wei et al. improved on existing Pt(II) organometallic complexes producing NIR emission between 866 and 960 nm, with a record photoluminescence quantum yield of 5%–12%, through exciton delocalization over numerous molecules ( Wei et al., 2020 ).…”
Section: Nir Light Sources and Detectionmentioning
Near-infrared (NIR) luminescent materials have emerged as a growing field of interest, particularly for imaging and optics applications in biology, chemistry, and physics. However, the development of materials for this and other use cases has been hindered by a range of issues that prevents their widespread use beyond benchtop research. This review explores emerging trends in some of the most promising NIR materials and their applications. In particular, we focus on how a more comprehensive understanding of intrinsic NIR material properties might allow researchers to better leverage these traits for innovative and robust applications in biological and physical sciences.
“…pointed out that such well-ordered packing produced weak electronic coupling, which contributed to efficient NIR emission. The Pt(II) complex named 4 t Bu has realized an EQE of 2.14% with a peak at 930 nm ( Wei et al., 2020 ). Figure 1 Jablonski diagram about triplet exciton utilization in pure organic system PF, DF, Ph, NR S , NR T , IC, ISC, RISC, hISC, and hRISC represent prompt fluorescence, delayed fluorescence, phosphorescence, singlet nonradiative transition, triplet nonradiative transition, internal conversion, intersystem crossing, reverse intersystem crossing, intersystem crossing from the higher singlet states, and RISC from the higher triplet states, respectively.…”
Section: Triplets Harvesting For High Device Efficiencymentioning
Near-infrared (NIR) emission is useful for numerous practical applications, such as communication, biomedical sensors, night vision, etc., which encourages researchers to develop materials and devices for the realization of efficient NIR organic light-emitting devices. Recently, the emerging organic thermally activated delayed fluorescence (TADF) emitters have attracted wide attention because of the full utilization of electron-generated excitons, which is crucial for achieving high device efficiency. Up to now, the TADF emitters have shown their potential in the deep red/NIR region. Considering the color purity and efficiency, however, the development of NIR TADF emitters still lags behind RGB TADF emitters, indicating that there is still much room to improve their performance. In this regard, this perspective mainly summarizes the past progress of molecular design on constructing TADF NIR emitters. We hope this perspective could provide a new vista in developing NIR materials and enlighten breakthroughs in both fundamental research and applications.
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