A New Strategy of bi-Alkali Metal Doping to Design Boron Phosphide Nanocages of High Nonlinear Optical Response with Better Thermodynamic Stability

Rimsha Baloach,Khurshid Ayub,Mazhar Amjad Gilani,Tariq Mahmood,Sobia Tabassum,Anila Asif

doi:10.1007/s10904-021-02000-6

Abstract

Nonlinear optical materials have gained immense scientific interest in the recent times owing to their vast applications in various fields. Continuous strides are made to design and synthesize materials with large nonlinear optical response and high thermodynamic stability. In this regard, we present here bi-alkali metal doping on boron phosphide nanocage as a new strategy to design thermodynamically stable materials with large nonlinear optical response. The geometric, thermodynamic, electronic, optical and nonlinear optical properties of complexes are explored through density functional theory (DFT) simulations. The doping of alkali metal atoms introduces excess of electrons in the host (B12P12) nanocage. These electrons contribute towards the formation of new HOMOs, which reduce the HOMO–LUMO gaps of the designed complexes. The HOMO–LUMO gaps of the designed complexes range from 0.63 eV to 3.69 eV. The diffused excess electrons also induce large hyperpolarizability values in the complexes i.e. up to 4.0 × 104au. TD-DFT calculations have been performed for crucial transition states and UV–VIS analysis. Non-covalent interaction (NCI) along with quantum theory of the atoms in molecules (QTAIM) analyses are carried out to understand the bonding interactions between alkali metal atoms and B12P12 nanocage. All the obtained results suggest that bi-alkali metal doped nanocages are exceptionally stable materials with improved NLO response.

Highlights

Nonlinear optical materials play important roles in this modern era of optics with their limitless utilization in different fields of science and technology[1]
First of all, pristine boron phosphide nanocage and alkali metal atoms were optimized and the computed results are comparable with already reported data[47][53]
The geometrical and electronic properties of bare nanocage are completely transformed when decorated with alkali metal atoms

Summary

Introduction

Nonlinear optical materials play important roles in this modern era of optics with their limitless utilization in different fields of science and technology[1]. Fullerenes are non-responsive towards NLO response and scientists have introduced numerous strategies to induce NLO response by both experimental and theoretical techniques These strategies include doping[31], electron push– pull mechanism[32], extensive π conjugation[33], utilization of bond length alteration theory (BLAT)[34], substitution effect[35], introduction of electron acceptor/donor group[36] and consideration of diradical character of materials[37]. Alkali metals have low ionization potential, valence electrons from these metal atoms are diffused out to act as excess electrons in materials This technique is being frequently used to design high performance[41] NLO materials. NBO analysis, dipole moment, polarizability and hyperpolarizability, NCI and QTAIM analysis are studied to get deep insight of NLO response of bi-alkali metal doped nanocage. NCI-RDG and AIM analysis were performed using MultiWfn software program in combination with visual molecular dynamic (VMD) software[64]

Results and Discussion

NCI-RDG Analysis

Conclusion