Two-dimensional hybrid chloride perovskite thin films by vapor transport

Organic-inorganic hybrid perovskite materials are transforming advanced functional materials, innovating solar cell, light-emitting devices and optoelectronics. This study introduces vapor transport deposition, which excels in controlling thin film composition and structure, to synthesize a 2D hybrid perovskite thin film, phenethylammonium lead chloride ((PEA)₂PbCl₄), via a multistage deposition process, highlighting scalable production potential. With parameter optimization, a PbCl₂ precursor thin film was deposited and converted to a perovskite phase through an intercalation reaction with phenethylammonium chloride (PEACl). X-ray diffraction, Rietveld refinement and VESTA simulations confirmed the 2D structure of the optimized (PEA)₂PbCl₄ thin film, featuring a single-layer inorganic octahedral arrangement (n = 1). Scanning electron microscopy revealed an initial uniform columnar morphology of the optimized PbCl₂ thin film (120 nm in diameter) and a woven-like morphology after conversion. The optical band gap, exciton binding energy and effective dimensionality were 3.644 eV, 20 meV and 2.64, respectively. The Urbach energy (E_U) was 620 meV, indicating some structural disorder. Photoluminescence spectroscopy showed broad self-trapped exciton emissions around 532 nm, attributed to intrinsic lattice distortions. These findings enhance understanding of 2D hybrid perovskite properties and highlight the scalable deposition method for diverse optoelectronic devices.