Laser ignition of energetic crystals involves coupled photophysical and chemical processes, beginning with photothermal conversion that transfers photoexcited-carrier energy to lattice vibrations and initiates local heating before decomposition. Here, first-principles calculations elucidate how intrinsic defects regulate this process in the quasi-two-dimensional molecular energetic crystal 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Atomic vacancies introduce in-gap states, with hydrogen vacancies efficiently trapping both electrons and holes and thereby promoting defect-assisted nonradiative recombination. Mode-resolved analysis shows that recombination at these defects preferentially couples to intramolecular vibrations associated with molecular deformation. By contrast, slower recombination in pristine TATB couples mainly to low-frequency interlayer collective modes, whose energy must be redistributed into higher-frequency intramolecular vibrations through phonon–phonon interactions. Thus, defects accelerate carrier-to-lattice energy transfer and directly channel the released energies into vibrations relevant to chemical-bond cleavage during the initial photothermal stage of laser ignition.

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• Electron-phonon coupling
• Electronic structure
• Energy applications
• Semiconductors
• Density functional theory
• First-principles calculations