Observation of self-polarization in BSA protected Au20 clusters

Bovine serum albumin (BSA)-protected gold clusters (atomicity ~ 20), prepared using a wet chemical route, show strong dipolar radiative transition with a gap energy of 1.93 eV due to the high oscillator strength, as confirmed by the emission studies. Self-arrangement of the clusters with fixed atomicity yields a low dispersive dielectric and electric self-polarization nature. The electrical hysteresis loop measurements returned a remanent polarization of 0.05 μC cm−2, which can be correlated with the dipolar orientation (activation energy ~ 45.32 meV), originating from the structure-dependent deformation of the charge density.