Highly efficient deep-blue photoluminescence (PL) of two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs) is critical for optoelectronic applications. However, the formation of lattice distortion–induced self-trapped excitons (STEs) and nonradiative recombination significantly impede the narrow-band deep-blue PL in 2D HOIPs. In the work reported here, pressure-induced enhanced deep-blue PL is achieved in 2D $(\mathrm{FIPA}{)}_2{\mathrm{Pb}\mathrm{Br}}_4$ (FIPA is 1,1,1-trifluoropropan-2-amine) perovskite. Notably, the narrow-band deep-blue PL intensity exhibits a 743-fold increase at 3.09 GPa. In situ Raman experiments and density-functional theory calculations confirm that enhanced intermolecular interaction forces and reduced inorganic $[{\mathrm{Pb}\mathrm{Br}}_6{]}^{4-}$ octahedral distortion under pressure lead to delocalization of STEs into free excitons (FEs). Furthermore, pressure-enhanced $\mathrm{C}$—$\mathrm{H}$···$\mathrm{Br}$ and $\mathrm{N}$—$\mathrm{H}$···$\mathrm{Br}$ hydrogen-bonding interactions inhibit the nonradiative recombination of FEs and STEs, which significantly increases the PL efficiency. This work may pave new pathways for the development of 2D perovskites with efficient and ultrapure deep-blue PL for further optoelectronic applications.

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• Carrier generation & recombination
• Chemical bonding
• Excitons
• Optoelectronics
• Pressure effects
• LEDs
• Organic-inorganic hybrid perovskites
• Photoluminescence