Single crystals of pure and crystal violet (CV) dye doped (0.05 mol%) ammonium dihydrogen phosphate (ADP) were grown and characterized. Structural and compositional studies were carried out using XRD, EDAX and FTIR. In UV-vis-NIR measurements, characteristic absorption at 590 nm was observed for CV dye, with increased transmittance, wider optical window and increased band gap from 5.80 eV to 6.0 eV. In photoluminescence studies, CV doping resulted in partial quenching of blue emission at 440 nm. The piezoelectric charge coefficient was also enhanced from 1.82 pC/N to 2.78 pC/N. In micro-hardness studies, CV doped crystals exhibited better mechanical strength. The distribution of hardness number was statistically analyzed using Weibull statistics. The values of transition point, critical load, etc. were evaluated for both the crystals. Raman studies revealed that no structural phase transformations were observed after indentation for both the samples. (C) 2016 Elsevier Ltd. All rights reserved.