Case Studies on Structure-Property Relations in Perovskite Light-Emitting Diodes via Interfacial Engineering with...

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Metal halide perovskites are promising for bright, narrow-band light-emitting diodes (LEDs).
• Understanding structure-property relationships in perovskites is challenging due to interwoven photophysical and electronic functions.
• Interfacial engineering is crucial for optimizing perovskite LED performance.

Purpose of the Study:

• To investigate the impact of self-assembled monolayers (SAMs) on perovskite film properties and LED performance.
• To elucidate the structure-property relationships in perovskite films by controlling interfacial chemistry.
• To enhance the external quantum efficiency (EQE) and narrow-band characteristics of perovskite LEDs.

Main Methods:

• Fabrication of SAMs using molecules with varying backbones and terminal groups on CH3NH3PbBr3 perovskite films.
• Comprehensive characterization using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Kelvin probe force microscopy (KPFM), scanning electron microscopy (SEM), and time-resolved laser spectroscopy.
• Evaluation of photophysical properties via UV-vis absorption and emission spectroscopies.

Main Results:

• SAMs modulated perovskite film quality, grain size, and cross-sectional atomic composition (Pb(0) vs Pb(II)).
• Interfacial engineering with SAMs influenced charge carrier lifetime and mobility.
• Enhanced external quantum efficiency (EQE) from 2.20% to 5.74% and narrowed emission linewidth from 21.3 nm to 15.9 nm.

Conclusions:

• The affinity of SAMs for undercoordinated Pb ions is key to improved perovskite film properties.
• SAM-based interfacial engineering effectively enhances EQE and narrow-band performance of perovskite LEDs without spectral shift.
• This approach offers a promising strategy for deciphering mechanisms and optimizing perovskite LED technology.