How to tame your bromine: bandgap tuning of solvent-free hybrid perovskites in a vapor transport deposition process
Year: 2026
Type: preprint
Abstract: We present a sequential physical vapor and gas phase transport deposition process for batchcapable formation of metal halide perovskite films, applicable to single- and multi-junction solar cells. After evaporating porous Cs-containing Pb halides via physical vapor deposition onto the substrate or bottom cell, we use a quartz furnace to deposit the organic precursor, formamidinium iodide (FAI), onto this inorganic scaffold via vapor transport deposition. Ammonia is used as carrier gas to prevent decomposition of FAI. The resulting perovskite is already present in the photoactive alpha phase. The process time can be minimized down to 15 min, depending on the scaffold, as no subsequent annealing is required. Notably all contacting layers in this work, including self-assembled molecules and passivation, are also fabricated with solvent-free processes. We note an occurring halide exchange reaction between the FAI in vapor phase and Br in the scaffold and present a proposed reaction scheme. By utilizing this reaction, we can vary the resulting bandgap of the perovskite to fit to the requirements for tandem applications, showing a broad process window. The resulting champion cell (1.66 eV) created with this approach reaches 18.3% power conversion efficiency, with a photoluminescence quantum yield of 1.6 % on full cell stacks.
Source: ChemRxiv
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Award: G971444140
OpenAlex ID: W7222433152