Fabrication of Potassium- and Rubidium-Doped Formamidinium
Lead Bromide Nanocrystals for Surface Defect Passivation and Improved
Photoluminescence Stability
posted on 2024-01-04, 20:44authored byMadeeha Tabassum, Qasim Zia, Huanqing Ye, William George Neal, Sameen Aslam, Jinshuai Zhang, Lei Su
The past decade has
seen a rapid development in metal halide perovskite
nanocrystals (NCs), which has been witnessed by their potential applications
in nanotechnology. The inimitable chemical nature behind their unique
photoluminescence characteristics has attracted a growing body of
researchers. However, the low intrinsic stability and surface defects
of perovskite NCs have hampered their widespread applications. Therefore,
numerous techniques such as doping and encapsulation (polymer matrices,
silica coating, salt matrix, etc.) have been examined for the surface
modification of perovskite NCs and to increase their efficiency and
stability. In this study, we demonstrated the self-passivation method
for surface defects by introducing potassium (K) or rubidium (Rb)
during the colloidal fabrication of NCs, resulting in the much-improved
crystallinity, photoluminescence, and improved radiative efficiency.
In addition, K-doped NCs showed a long-term colloidal stability of
more than 1 month, which indicates the strong bonding between the
NCs and the smaller-sized potassium cations (K+). We observed
the enhancement of the radiative lifetime that can also be explained
by the prevention of “Frenkel defects” when K+ stays at the interstitial site of the nanocrystal structure. Furthermore,
our current findings signify the importance of surface modification
techniques using alkali metal ions to reduce the surface traps of
perovskite nanocrystals (PeNCs). Comparable developments could be
applied to polycrystalline perovskite thin films to reduce the interface
trap densities. The findings of this study have several important
implications for future light-emitting applications.