عنوان

Design Principles for Trap-Free CsPbX3 Nanocrystals:

Number

LA0nk4w4z1

Title Proper

Design Principles for Trap-Free CsPbX3 Nanocrystals:

General Material Designation

[Article]

First Statement of Responsibility

Nenon, David PPressler, KimoKang, JunKoscher, Brent AOlshansky, Jacob HOsowiecki, Wojciech TKoc, Matthew AWang, Lin-WangAlivisatos, A Paul

Title Proper by Another Author

Enumerating and Eliminating Surface Halide Vacancies with Softer Lewis Bases.

Text of Note

We introduce a general surface passivation mechanism for cesium lead halide perovskite materials (CsPbX3, X = Cl, Br, I) that is supported by a combined experimental and theoretical study of the nanocrystal surface chemistry. A variety of spectroscopic methods are employed together with ab initio calculations to identify surface halide vacancies as the predominant source of charge trapping. The number of surface traps per nanocrystal is quantified by 1H NMR spectroscopy, and that number is consistent with a simple trapping model in which surface halide vacancies create deleterious under-coordinated lead atoms. These halide vacancies exhibit trapping behavior that differs among CsPbCl3, CsPbBr3, and CsPbI3. Ab initio calculations suggest that introduction of anionic X-type ligands can produce trap-free band gaps by altering the energetics of lead-based defect levels. General rules for selecting effective passivating ligand pairs are introduced by considering established principles of coordination chemistry. Introducing softer, anionic, X-type Lewis bases that target under-coordinated lead atoms results in absolute quantum yields approaching unity and monoexponential luminescence decay kinetics, thereby indicating full trap passivation. This work provides a systematic framework for preparing highly luminescent CsPbX3 nanocrystals with variable compositions and dimensionalities, thereby improving the fundamental understanding of these materials and informing future synthetic and post-synthetic efforts toward trap-free CsPbX3 nanocrystals.

Date of Publication

2018

Title

Lawrence Berkeley National Laboratory

Electronic name

[Article]

278465

a

Y