The Two-Photon Absorption Cross-Section Studies of CsPbX3 (X = I, Br, Cl) Nanocrystals.

Janusz Szeremeta,Marcin Nyk,Marek Samoć,Dominika Wawrzyńczyk,Magda A Antoniak

doi:10.3390/nano10061054

Abstract

The CsPbX3 nanocrystals (NCs) with X = I, Br, Cl, or the mixture of Br:I and Br:Cl in a 1:1 ratio were synthesized and characterized by TEM, DLS, and XRD. Recrystallization of the small luminescent NCs in the metastable cubic phase into bigger orthorhombic nanocrystals was monitored by XRD and identified as the main cause of the nanocolloid coagulation. The recrystallization also leads to a decrease in the photoluminescence quantum yield (QY) of the colloidal solution and shortening of the emission lifetime. The two-photon absorption cross-section σ2 values calculated from femtosecond Z-scan measurements were compared with those obtained based on the two-photon excited emission technique. These two techniques were shown to be equivalent with the cross-section values calculated per molar mass of CsPbX3 perovskite being in the range of 10–200 GM depending on the halide anions X−. The σ2 values recalculated for the mole of the NCs were in the range of 104–105 GM, which is in good agreement with values previously reported elsewhere and the σ2/M parameter was in the range of 0.01 to 0.33. This study shows the perovskite NCs to be a good nonlinear material with the third-order nonlinear optical susceptibility χ(3) of the NCs on the order of 10−11 esu.

Highlights

In the last few years, perovskite materials such as hybrid organic-inorganic lead halide perovskites (CH3NH3PbX3, X = I, Br, Cl), and in particular their nanosized colloidal particles, gained great interest for application in third-generation solar cells, whose efficiency can exceed 20% [1,2,3]
This is the ratio of lead halides used for the synthesis and we assume that the lead halides were completely reacted because the Cs precursor was uNsaneodmianterdiaolsu2b02le0,e1x0,cxesFsO.R PEER REVIEW
Based on the X-ray diffraction (XRD) studies their colloidal instability was proven to be due to change in the crystallographic phase from cubic to orthorhombic, which is known to be the perovskite stable phase at room temperature

Summary

Introduction

In the last few years, perovskite materials such as hybrid organic-inorganic lead halide perovskites (CH3NH3PbX3, X = I, Br, Cl), and in particular their nanosized colloidal particles, gained great interest for application in third-generation solar cells, whose efficiency can exceed 20% [1,2,3]. These newly developed semiconducting materials exhibit strong light absorption, small exciton binding energies, high charge carrier mobility, as well as long charge carrier diffusion length [3]. Two-photon pumping has become a viable technique for the generation of coherent light by the optical gain in colloidal semiconductor NCs [15]

Methods

Results

Conclusion