Absolute Photoluminescence Quantum Yields of IR-26 Dye, PbS, and PbSe Quantum Dots

Abstract

In this study, we have directly measured the photoluminescence quantum yield (Φ PL ) of IR-26 at a range of concentrations and the Φ PL of PbS and PbSe QDs for a range of sizes. We find that the Φ PL of IR-26 has a weak concentration dependence due to reabsorption, with a Φ PL of 0.048 ( 0.002% for low concentrations, lower than previous reports by a full order of magnitude. We also find that there is a dramatic size dependence for both PbS and PbSe QDs, with the smallest dots exhibiting a Φ PL in excess of 60%, while larger dots fall below 3%. A model, including nonradiative transition between electronic states and energy transfer to ligand vibrations, appears to explain this size dependence. These findings provide both a better characterization of photoluminescence for nearinfrared emitters and some insight into how improved QDs can be developed. SECTION Nanoparticles and Nanostructures

PbSe/CdSe Thin-Shell Colloidal Quantum Dots

“…In Figure 8A, the PL QY values for PbSe/CdSe core/shell CQD samples withdrawn from the reaction mixture and measured after different periods of cation exchange (red symbols) are compared with the PL QY values for different-sized PbSe CQDs (blue symbols) with the same values. In both cases, almost the same gradual increase of PL QY is observed with the increase of up to a certain "turning point" (∼ 1.3 eV), which may be associated with the increase of the oscillator strength in the CQDs, as reported previously [51,59]. However, above the "turning point" a drastic increase of PL QY is observed in the PbSe/CdSe CQDs, the QY values being much larger than those estimated based on the oscillator strength trend.…”

Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

“…Finally, the EQE depends on the size of the quantum dots, even for a fixed linker. Although the measured EQE fluctuated from device to device, the overall trend was that the EQE decreased as quantum-dot size increased (see Supplementary Section SD), which is consistent with the trend for photoluminescence quantum efficiency 21 . The highest EQE (2.0+0.3%) was obtained from MOA-capped quantum dots, with an emission peak at 1,054 nm (Fig.…”

Kinetic analysis of the temperature dependence of PbSe colloidal quantum dot photoluminescence: Effects of synthesis process and oxygen exposure

“…B 4 Two hours of air exposure as drop cast, none during QD synthesis; Chappell et al [10]. B 5 Twelve hours of exposure as drop cast, none during QD synthesis; Chappell et al [10]. C 1 No air exposure as drop cast, some during QD synthesis; Qiao et al [8].…”

“…The near-infrared photoluminescence (PL) from PbSe and PbSe/CdSe colloidal quantum dots (QDs) with diameters on order 4-6 nm has been studied extensively in solution [1][2][3][4][5] but less so out of solution, where significant applications also exist [6][7][8][9][10][11]. One obstacle that has hindered progress in gaining a quantitative microscopic understanding of the optical emission from this material system has been the lack of consistency of the experimental results reported by different groups.…”