Sonocrystallization of Lead-free layered Ruddlesden-Popper like 2-D hybrid halide perovskite as a light harvester for photovoltaics

A paramount of interest has been paid towards toxic lead free low -dimensional hybrid organic -inorganic halide perovskites due to their remarkable optoelectronic properties which are concerned over long-term stability and toxicity. As a matter of fact, we present optimized ultrasonic assisted wet chemical method for the synthesis of lead-free layered Ruddlesden-Popper like 2-D methylammonium copper chloride perovskites. The influence of sonication time as a simple yet effective key operating parameter to tune morphology and size thereby variation in band gap has been studied. As a consequence, sonocrystallised perovskites featured significant differences in optoelectronic properties and conductive nature. All of which are evidenced by analytical techniques such as PXRD, UV - Vis DRS, PL, FE-SEM, HR-TEM with EDAX, simultaneous TGA-DSC, XPS, EIS and I - V characteristics. The as -synthesized perovskites shown bandgap variation from 2.12 eV to 2.27 eV. An indirect approach is used to measure Urbach energy and is found to vary from 198 meV to 324 meV. Steady-state PL results show lower intensity with increase in sonication time. X-ray diffractograms revealed the crystallite size reduction along (001) basal direction with increasing sonication time with no evidence for structural change. The Williamson -Hall plot results reveal that crystallite size decreases and micro -strain increases as a function of sonication time. A keen observation on FE-SEM and HR-TEM results revealed about mechanism of sonocrystallization. Simultaneous TGA-DSC was carried out which confirms the stability above 200 degrees C. Improved electronic properties have been verified by EIS and I - V characteristics.