Inorganic perovskites improved film and crystal quality of CsPbIBr2 when doped with rubidium

Abstract

In this work CsPbIBr2 is doped with rubidium, where up to 12% of caesium atoms are replaced with those of rubidium. The obtained Cs1 − xRbxPbIBr2, x= (0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.12), films were characterized by X-ray diffraction (XRD), the scanning electron microscope (SEM), photoluminescence (PL) and UV–visible spectroscopy. The integration of Rb+ ions into the lattice leads to a detectable change in optoelectronic and morphological structure. Substituting 6% of caesium atoms yields the best results, eliminating pinholes and elevating crystallite size and absorption coefficient by 116 and 125%, respectively. Other novel observations, of particular interest, include a slight increase in band-gap energy from 2.1 eV to 2.14 eV and a decrease in stability. Over a period of 15 days, where temperature and relative humidity kept at 23 °C and 20%, respectively, a larger amount of degradation was seen to take place as rubidium content was increased. Therefore, the doping of CsPbIBr2 with rubidium is most useful in the case where specifically film and crystal quality are desired to be targeted.