Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr₃ Perovskite Nanocrystals

Journal Article · Wed May 16 00:00:00 EDT 2018 · Journal of Physical Chemistry. C

DOI:https://doi.org/10.1021/acs.jpcc.8b03206· OSTI ID:1530363

Gibson, Natalie A.  ^[1]; Koscher, Brent A.  ^[2]; Alivisatos, A. Paul  ^[2]; Leone, Stephen R.  ^[1]

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1. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoScience Inst., Berkeley, CA (United States)

Perovskite semiconductors have emerged as a promising class of materials for optoelectronic applications. Their favorable device performances can be partly justified by the defect tolerance that originates from their electronic structure. The effect of this inherent defect tolerance, namely the absence of deep trap states, on the photoluminescence (PL) of perovskite nanocrystals (NCs) is currently not well understood. The PL emission of NCs fluctuates in time according to power law kinetics (PL intermittency, or blinking), a phenomenon that has been explored over the past two decades in a vast array of nanocrystal (NC) materials. The kinetics of the blinking process in perovskite NCs have not been widely explored. Here, PL trajectories of individual orthorhombic cesium lead bromide (CsPbBr₃) perovskite NCs are measured using a range of excitation intensities. The power law kinetics of the bright NC state are observed to truncate exponentially at long durations, with a truncation time that decreases with increasing intensity before saturating at an intensity corresponding to an average formation of a single exciton. The results indicate that a diffusion-controlled electron transfer (DCET) mechanism is the most likely charge trapping process, while Auger autoionization plays a lesser role. The relevance of the multiple recombination centers (MRC) model to the results presented here cannot be ascertained, since the underlying switching mechanism is not currently available. Further experimentation and theoretical work are needed to gain a comprehensive understanding of the photophysics in these emerging materials.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1530363
• Journal Information: Journal of Physical Chemistry. C, Vol. 122, Issue 22; ISSN 1932-7447
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY