Recombination, multiplication, and transfer of electron-hole pairs in silicon nanocrystals: Effects of quantum confinement, doping, and surface chemistry

Derbenyova, Natalia V.; Konakov, A. A.; Бурдов, В. А.

doi:10.1016/j.jlumin.2021.117904

Cited by 7 publications

(6 citation statements)

References 178 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…DFT calculations indicate that the Cl group of a SiQD reduces the Auger process. 61,62 This result is in good agreement with both the high EQE of the LED prepared from RT-SiQDs with Cl groups. Third, the EQE between the two SiQD LEDs depended on the current density, and a lower current density resulted in significantly high EQE of RT-SiQD LEDs, as shown in Figure 8f.…”

Section: Resultssupporting

confidence: 84%

“…According to the results of DFT calculations, the Cl ligands on the SiQDs reduce Auger recombination of the nonradiative process (vide infra). 61,62 If this scenario is applied to the present study, the 4% surface coverage of Cl ligands on the RT-SiQDs would essentially reduce the nonradiative process by half. In this situation, the 20× difference in EL intensity between the two LEDs originated from the 10× difference in current density at 8 V and the 2× difference in Auger recombination of the nonradiative process.…”

Section: Resultsmentioning

confidence: 99%

“…The Cl ligand is known to reduce the Auger process, which hinders recombination between electrons and holes (vide infra). 61,62 Next, EF as a function of the applied voltage also provides revealing information that may aid in the design of SiQD LEDs. The EF was 10−40 times higher than the baseline for voltages over 3 V, and reached a maximum at 5.5 V, as shown in the inset of Figure 8a.…”

Section: Resultsmentioning

confidence: 99%

“…SiQDs terminated by hydrosilylation with PCl 5 exhibit 2.6 times higher PLQYs (62%) than those terminated by thermal hydrosilylation (24%) . Research using DFT calculations demonstrated that the termination of small amounts of Cl atoms as well as electronegative ligands enhances the PL radiative rate of a SiQD. Another DFT calculation showed that Cl atoms bonded onto a SiQD reduced Auger recombination, a nonradiative process. , The results obtained from these three previous studies were in good agreement with the present results.…”

Section: Resultsmentioning

confidence: 99%

“…Research using DFT calculations demonstrated that the termination of small amounts of Cl atoms as well as electronegative ligands enhances the PL radiative rate of a SiQD. Another DFT calculation showed that Cl atoms bonded onto a SiQD reduced Auger recombination, a nonradiative process. , The results obtained from these three previous studies were in good agreement with the present results. In fact, enhancements of both the PLQY and the radiative rate and the reduction in the nonradiative rate were observed in the RT-SiQDs with Cl ligands.…”

Section: Resultsmentioning

confidence: 99%

See 4 more Smart Citations

Designing Efficient Si Quantum Dots and LEDs by Quantifying Ligand Effects

Ono

Sakata

et al. 2021

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

The impact of colloidal silicon quantum dots (SiQDs) on next-generation light sources is promising. However, factors determining the efficiency of SiQDs, such as the photoluminescence (PL) wavelength, PL quantum yield (PLQY), and the SiQD LED performance based on the type of ligand, ligand coverage, stress, and dangling bonds, have not been quantified. Characterizing these variables would accelerate the design and implementation of SiQDs. Herein, colloidal SiQDs were synthesized by pyrolyzing hydrogen silsesquioxane and their surfaces were terminated with 1-decene by either thermal hydrosilylation (HT-SiQDs) or room-temperature hydrosilylation using PCl 5 (RT-SiQD). As a result, PL, PL-excitation, and ultraviolet−visible absorption spectra were similar, but their PLQYs were significantly different: 54% (RT-SiQDs) vs 19% (HT-SiQDs). To understand their similarities and differences, surface coverages (dangling bonds, Si−H (Si−H 1 , Si−H 2 , and −Si−H 3 ), Si−O−Si, Si−C, Si−Cl) were determined. A core stress analysis established that a single ligand terminated to a SiQD bond site stretched the Si−Si bond length by 0.3%. From the two well-defined SiQDs, the PLQY and SiQD LED efficiency were attributed to four factors: low coverage of insulator ligands, the Cl ligand effect on radiative and nonradiative rates, negligible dangling bonds, and a SiQD core with low tensile stress. The PLQY of the RT-SiQDs in toluene was 80%. In addition, the 20× electroluminescence intensity difference of the LEDs originated from a 10× difference in current density and a 2× difference in Auger recombination. The concepts demonstrated here can be applied to further improve the PLQY and LED efficiencies of SiQDs with other ligands.

show abstract

Section: Resultssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%