Remanent Polarization and Strong Photoluminescence Modulation by an External Electric Field in Epitaxial CsPbBr3 Nanowires.

Ella Sanders,Dan Oron,Tommaso Salzillo,Maor Rosenberg,Yahel Soffer,Omri Bar-Elli,Ernesto Joselevich,Omer Yaffe

doi:10.1021/acsnano.1c04905

Abstract

Metal halide perovskites (MHPs) have unique characteristics and hold great potential for next-generation optoelectronic technologies. Recently, the importance of lattice strain in MHPs has been gaining recognition as a significant optimization parameter for device performance. While the effect of strain on the fundamental properties of MHPs has been at the center of interest, its combined effect with an external electric field has been largely overlooked. Here we perform an electric-field-dependent photoluminescence study on heteroepitaxially strained surface-guided CsPbBr3 nanowires. We reveal an unexpected strong linear dependence of the photoluminescence intensity on the alternating field amplitude, stemming from an induced internal dipole. Using low-frequency polarized-Raman spectroscopy, we reveal structural modifications in the nanowires under an external field, associated with the observed polarity. These results reflect the important interplay between strain and an external field in MHPs and offer opportunities for the design of MHP-based optoelectronic nanodevices.

Highlights

The promising optoelectronic properties of metal halide perovskites (MHPs) have led to extensive research aiming to discover the source of their extraordinary performance and to fulfill their potential as building blocks for optoelectronic devices, including photovoltaics, light sources, and detectors
This introduces strain in the CsPbBr3 crystal lattice, which is highest at the interface with the sapphire and gradually decreases toward the top of the nanowire.[6]
In order to investigate the effect of an external electric field (E-field) on the properties of the strained nanowires, we fabricated an array of two-electrode devices, such that the nanowire’s long axis is parallel to the E-field lines (Figure 1c−e)

Summary

Introduction

The promising optoelectronic properties of metal halide perovskites (MHPs) have led to extensive research aiming to discover the source of their extraordinary performance and to fulfill their potential as building blocks for optoelectronic devices, including photovoltaics, light sources, and detectors. MHPs’ properties may be significantly influenced by the presence of lattice strain, especially in light of their mechanically soft nature.[1] While mismanaged strain can often lead to defect formation and material degradation, strain engineering can introduce beneficial effects.[2,3] One of the most common techniques in use is heteroepitaxial strain engineering, where the strain is created due to a lattice mismatch between a crystalline substrate and the desired epilayer While this technique has evolved as a powerful tool in MHPs,[2] it is currently limited to the case of low lattice mismatch with the substrate, often not available when designing efficient devices. The influence of strain on the intrinsic properties of MHPs is gaining interest, the effect of an applied electric field (E-field) on a strained system has been largely overlooked

Methods

Results

Conclusion