Polaronic Signatures in Doped and Undoped Cesium Lead Halide Perovskite Nanocrystals through a Photoinduced Raman Mode.
Priyanka JainMadhulika MazumderK R PradeepRanjani ViswanathaSwapan K PatiChandrabhas NarayanaPublished in: ACS applied materials & interfaces (2022)
Lead halide perovskites (LHPs) are promising candidates for photovoltaic applications as they exhibit large carrier diffusion lengths and long carrier lifetimes among many other interesting properties. One of the widely accepted mechanisms for these properties is polaron formation, which is mainly driven by octahedral distortions of the inorganic framework. Since structure modifications of the framework largely affect associated distortions, we investigated Mn-doped and undoped CsPbX 3 (where X = Cl, Br, Cl/Br) using a local probe via micro-Raman spectroscopy and density functional theory (DFT) calculations for polaron formation. Our results highlight a new vibrational lattice mode at 132 cm -1 due to polaronic distortion upon photoinduction. From the DFT studies, we have shown that the polaronic states are dominated by the B-site cation in the perovskite structure, but it is the strong covalent overlap of the halide which determines its stability. This elucidation to map polaronic signatures with excellent spatial resolution using traditional Raman spectroscopy can be used as a simple tool to understand the structural changes and their impacted electronic properties and thus design superior devices using its in situ applications.
Keyphrases
- density functional theory
- raman spectroscopy
- solar cells
- molecular dynamics
- quantum dots
- room temperature
- perovskite solar cells
- metal organic framework
- genome wide
- highly efficient
- ionic liquid
- single molecule
- gene expression
- living cells
- high efficiency
- mass spectrometry
- visible light
- case control
- water soluble
- electron transfer