Despite their similar chemical structures, MeTPA-BQ and tBuTPA-BQ possess distinctly different photophysical properties in the crystalline states, which are attributed to their different solid-state packing. Notably, TPPA-BQ represents the first example of a TADF material that displays such a large piezochromic shift of 165 nm, into the near-infrared region. The changes in the photophysical properties of TPPA-BQ were found to be completely reversible upon grinding and ethyl acetate solvent fuming. MeTPA-BQ and tBuTPA-BQ were employed as emitters in the fabrication of deep red OLEDs showing EQEmax of 10.1% (λEL = 650 nm) and 8.5% (λEL= 670 nm), respectively.