Direct probe of spectral inhomogeneity reveals synthetic tunability of single-nanocrystal spectral linewidths

• Published in: Nature chemistry 2013-07, Vol.5 (7), p.602-606
• Main Authors: Cui, Jian, Beyler, Andrew P., Marshall, Lisa F., Chen, Ou, Harris, Daniel K., Wanger, Darcy D., Brokmann, Xavier, Bawendi, Moungi G.
• Format: Article
• Language: English
• Subjects: 639/638/298/398; 639/638/440/527; 639/925/357; Analytical Chemistry; Atoms & subatomic particles; Biochemistry; Cadmium Compounds - chemistry; Chemistry; Chemistry/Food Science; Correlation analysis; Energy; Fourier transforms; Inorganic Chemistry; Nanocrystals; Nanoparticles; Nanotechnology; Organic Chemistry; Physical Chemistry; Quantum dots; Selenium Compounds - chemistry; Spectrometry, Fluorescence; Spectroscopy; Statistics; Sulfides - chemistry
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/nchem.1654

The spectral linewidth of an ensemble of fluorescent emitters is dictated by the combination of single-emitter linewidths and sample inhomogeneity. For semiconductor nanocrystals, efforts to tune ensemble linewidths for optical applications have focused primarily on eliminating sample inhomogeneities, because conventional single-molecule methods cannot reliably build accurate ensemble-level statistics for single-particle linewidths. Photon-correlation Fourier spectroscopy in solution (S-PCFS) offers a unique approach to investigating single-nanocrystal spectra with large sample statistics and high signal-to-noise ratios, without user selection bias and at fast timescales. With S-PCFS, we directly and quantitatively deconstruct the ensemble linewidth into contributions from the average single-particle linewidth and from sample inhomogeneity. We demonstrate that single-particle linewidths vary significantly from batch to batch and can be synthetically controlled. These findings delineate the synthetic challenges facing underdeveloped nanomaterials such as InP and InAs core–shell particles and introduce new avenues for the synthetic optimization of fluorescent nanoparticles. The average single-nanocrystal spectral linewidth within an ensemble of nanocrystal emitters in solution can be directly and quantitatively measured using photon-correlation Fourier spectroscopy (S-PCFS). Variations in single-nanocrystal linewidths between batches are found to be significant and synthetically tunable, introducing new avenues for the optimization of nanocrystals for optical applications.