# Monodisperse spherical Ag+ doped Cs2KBiCl6 nanocrystals: utilizing steric hindrance engineering for inkjet printing of anti-counterfeiting patterns

## TL;DR

Researchers created tiny, spherical nanocrystals that emit orange light when exposed to UV light, which can be printed into anti-counterfeiting patterns.

## Contribution

A propagable method for synthesizing Ag+ doped Cs2KBiCl6 nanocrystals with steric hindrance engineering for inkjet printing applications is introduced.

## Key findings

- Monodisperse spherical Ag+ doped Cs2KBiCl6 nanocrystals with an average diameter of 3.51 nm were successfully synthesized.
- The nanocrystals exhibit orange emission peaking at 600 nm under 365 nm UV excitation.
- A printable ink was developed using the nanocrystals for inkjet printing of anti-counterfeiting patterns.

## Abstract

Anti-counterfeiting is one of the critical application fields of luminescent materials. Nanocrystal luminescent materials are more suitable for anti-counterfeiting applications because they are tiny and more conducive to patterning. The preparation of monodisperse and spherical lead-free perovskite nanocrystals by a propagable method is a hot topic in anti-counterfeiting materials. In this work, monodisperse spherical Ag+ doped Cs2KBiCl6 nanocrystals with an average diameter of 3.51 nm were prepared by using the propagable ligand-assisted reprecipitation method at room temperature, attributed to steric hindrance engineering by increasing the ligand size. Due to relaxation of the transition barrier due to doping, excited with 365 nm ultraviolet light, the nanocrystals exhibit orange emission peaking at 600 nm, which is related to the transition recombination of Bi3+ (1S0 → 3P1), and the maximum photoluminescence quantum yield is 3.80%. A printable ink is prepared by combining the nanocrystals with PDMS adhesive and its curing agent, which can be used for inkjet printing of anti-counterfeiting patterns.

Monodisperse spherical Ag+ doped Cs2KBiCl6 nanocrystals are used to prepare an inkjet printable ink for anti-counterfeiting patterns.