Effective Stabilization of Perovskite Cesium Lead Bromide Nanocrystals through Facile Surface Modification by Perfluorocarbon Acid.

Daichi Sato,Yoshiki Iso,Tetsuhiko Isobe

doi:10.1021/acsomega.9b03472

Abstract

CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs) have attracted much attention as promising materials for next-generation optoelectronic applications. However, improvement of their low stabilities against heating and humidity is needed for practical use. In this work, we focused on perfluorodecanoic acid (PFDA) as a surface ligand and investigated the thermal and chemical stabilities of the photoluminescence (PL) properties of CsPbBr3 NCs. Oleic acid (OA) adsorbed on the NCs was exchanged for decanoic acid (DA) and PFDA. OA-modified and DA-modified NCs exhibited drastic fluorescence quenching to 12.9 and 21.1% of their initial PL intensities, respectively, after heating at 100 °C for 4 h. In contrast, the PFDA-modified NCs maintained 92.1% of their PL intensity after the same heating. Furthermore, the polar solvent resistance was also improved by PFDA modification. These improvements can be attributed to the strong adsorptivity and high chemical stability of the PFDA ligand.

Highlights

We investigated the effects of perfluorodecanoic acid (PFDA) modification on the thermal stability and polar solvent resistance of CsPbBr3 NCs
PFDA has a higher adsorptivity than other carboxylic acids, such as Oleic acid (OA) and decanoic acid (DA), because of its lower pKa
After heating at 100 °C for 4 h, the PL intensity was maintained at 92.1% of the initial intensity, whereas the OA-NCs and DA-NCs exhibited drastic PL quenching to 12.9 and 21.1% of the initial value, respectively

Summary

INTRODUCTION

Lead halide perovskites have been intensely researched as materials for next-generation optoelectronic applications, such as solar cells,[1−5] light-emitting diodes,[6−11] wide color gamut displays,[12−14] photodetectors,[10,15−17] and lasers.[18−21] Lead halide perovskites are classified as organic−inorganic and allinorganic materials based on their elemental composition.[12]. When TOP was added to the NC dispersion, the PL intensity at 90 °C was 43% of the initial intensity at 20 °C, followed by recovery to 93% after cooling to 20 °C, revealing that the TOP modification suppressed the thermal damage of the NCs. Luminescent materials used in optoelectronic devices are inevitably heated; improvement of the important issue.[44−46] thermal stability of. Changes in the particle morphology and optical properties under heating by ligand exchange of OA for PFDA and DA were evaluated Another significant problem of CsPbBr3 NCs is their remarkably low stability against polar solvents.[41] We assumed that surface modification with fluorocarbon acids will protect CsPbBr3 NCs from serious damage by polar solvents; the effect of PFDA modification on the polar solvent resistance of the NCs was evaluated

RESULTS AND DISCUSSION

CONCLUSIONS

EXPERIMENTAL SECTION

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