Challenge to the charging model of semiconductor-nanocrystal fluorescence intermittency from off-state quantum yields and multiexciton blinking.
نویسندگان
چکیده
Semiconductor nanocrystals emit light intermittently; i.e., they "blink," under steady illumination. The dark periods have been widely assumed to be due to photoluminescence (PL) quenching by an Auger-like process involving a single additional charge present in the nanocrystal. Our results challenge this long-standing assumption. Close examination of exciton PL intensity time traces of single CdSe(CdZnS) core(shell) nanocrystals reveals that the dark state PL quantum yield can be 10 times less than the biexciton PL quantum yield. In addition, we observe spectrally resolved multiexciton emission and find that it also blinks with an on/off ratio greater than 10:1. These results directly contradict the predictions of the charging model.
منابع مشابه
Many-Body Processes in the Photophysics of Colloidal Semiconductor Nanocrystals
In this work we have experimentally studied several aspects of two Coulomb processes that change the number of electrons and holes in colloidal semiconductor nanocrystals (NCs). Carrier Multiplication (CM) is the production of additional electron-hole pairs by collision of a highly excited carrier with valence electrons. Efficient CM would improve the performance of solar energy conversion devi...
متن کاملMechanisms of fluorescence blinking in semiconductor nanocrystal quantum dots.
The light-induced spectral diffusion and fluorescence intermittency (blinking) of semiconductor nanocrystal quantum dots are investigated theoretically using a diffusion-controlled electron-transfer (DCET) model, where a light-induced one-dimensional diffusion process in energy space is considered. Unlike the conventional electron-transfer reactions with simple exponential kinetics, the model n...
متن کاملConfocal Microscopy Studies of Fluorescence Blinking of Semiconductor Quantum Dots, Metal Nanoparticle Photogeneration, and Multiphoton Photoemission from Thin Metal Films and Metal Nanoparticles
Since the advent of single molecule spectroscopy in 1989, advances in the field have revealed a wealth of information on dynamics and sample heterogeneity unobtainable by traditional ensemble studies. Microscopy experiments are a common technique to characterize and probe single molecule dynamics, due to the combination of the diffraction limited spatial resolution and the availability of sensi...
متن کاملEnhanced Fluorescence Blinking of CdSe / ZnS Quantum Dot Clusters
Submitted for the MAR07 Meeting of The American Physical Society Enhanced Fluorescence Blinking of CdSe/ZnS Quantum Dot Clusters MING YU, ALAN VAN ORDEN, Colorado State University — Semiconductor quantum dots (QDs) have been studied for many years to understand their unique, size tunable optical properties, and to investigate their potential applications in optoelectronic devices and biological...
متن کاملSurface Charge Control of Quantum Dot Blinking
A characteristic property of colloidal semiconductor nanocrystal quantum dots (QDs) is their emission intermittency. Although a unifying theory of QD photoprocesses remains elusive, the importance of charged states is clear. We now report a new approach to directly study the role of surface charge on QD emission by adding metal ions to individual, core-only QDs immobilized in aqueous solution i...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review letters
دوره 104 15 شماره
صفحات -
تاریخ انتشار 2010