Additive engineering in CH3NH3PbBr3 single crystals for terahertz devices and tunable high-order harmonics

Abstract

Although organic–inorganic hybrid perovskites (OIHPs) are considered frontline candidates owing to their intriguing optoelectronic properties, their unstable surfaces are prone to degradation, significantly affecting device performance and hence limiting their commercialization. Additive engineering has become the most effective strategy to improve the quality of 3D perovskite single crystals (PSCs). Herein additive engineering employing various aliphatic, aromatic, and chiral ammonium salts results in high-quality transparent methylammonium lead bromide (MAPbBr₃) PSCs, which are demonstrated for application in terahertz (THz) devices, besides being sources for high-order harmonics generation (HHG). Remarkably the engineered crystal surfaces showed resistance to surface degradation compared to pristine ones, thereby enhancing the transmission/reflection of THz pulses. Moreover, a noticeable blue shift in harmonics (both nano second (ns) and pico second (ps) laser induced plasmas (LIPs)) was achieved compared to pristine MAPbBr₃ (MA). The current research is anticipated to open up new sources of additive-based SCs to be used entirely for THz devices and tunable high-order harmonic generation avenues. Exploring these inanimate materials via additive inclusion in MA SCs opens up new avenues to achieve blue-shifted UV spectra for diverse applications in attosecond physics and nonlinear spectroscopy, including tunable THz devices because of the easy tunability of the THz absorption properties, i.e. their phonon modes in an OIHPSC.