Solution Processed Hybrid Lead Perovskite Films for White Light Emission and Lasing Applications

Subhadip Chowdhury, Mrinmay K Mukhopadhyay, Milan K Sanyal, Satyaban Bhunia,
Biswarup Satpati, Rajendra P Giri, B Bharatiya, Chen Shen and Bridget M Murphy

Organic-inorganic hybrid lead-halide perovskite films in two dimensions (2D) are intriguing optoelectronic
materials with a range of technological uses, such as lasing and white-light emission. The research
group of Dr. Mrinmay K. Mukhopadhyay, SPMS Division, SINP has shown that nanometer-thick films of 2D
perovskite materials can be prepared at ambient temperature from the solution of butylammonium
lead-bromide [(BA)₂PbBr₄] flakes in water using Langmuir-Schaefer (LS) deposition method. For that
purpose, the stearic acid molecules were dispersed as the surfactants on the water subphase, and the
DMF solution of the butylammonium lead-bromide perovskite was mixed in the water sub-phase. The
in-situ X-ray measurements were performed at the PETRA-III x-ray synchrotron source at DESY, Germany
to show how the Langmuir monolayer of the molecular assembly is being formed at the air-water interface.
The surface morphology and the crystallinity of the transferred nanofilms onto the substrate were
investigated using atomic force microscopy, transmission electron microscopy, and X-ray diffraction
experiments. The temperature-dependent photoluminescence experiment reveals unprecedented broad
white light emission with a strong band-edge transition from the perovskite nanofilms in comparison to the
sharp emission in the blue region from the perovskite flakes. The perovskite flakes display lasing which is
not possible in the transferred LS nanofilms as their thicknesses are lower than the lasing wavelength
prohibiting wave-guide formation without external cavities. The results show that the 2D single-crystalline
nature of the LS films and flakes are suitable materials to develop broad-band white light emission across
the entire visible range and to obtain lasing without external cavities, respectively.

The paper has been published in Advanced Functional Materials

Link : https://doi.org/10.1002/adfm.202401334