Remarkable static and dynamic NLO response of alkali and superalkali doped macrocyclic [hexa-]thiophene complexes; a DFT approach.

Hasnain Sajid,Khurshid Ayub,Faizan Ullah,Tariq Mahmood,Sidra Khan,Muhammad Arshad

doi:10.1039/d0ra08099c

Hasnain Sajid, Khurshid Ayub + Show 4 more

Open Access

https://doi.org/10.1039/d0ra08099c

Copy DOI

Abstract

In this study, the nonlinear optical (NLO) response of alkali metal atom (Li, Na and K) and their corresponding superalkali (Li3O, Na3O and K3O) doped six membered cyclic thiophene (6CT) has been explored. The optimized geometries of complexes; Li@6CT, Na@6CT, K@6CT, Li3O@6CT, Na3O@6CT and K3O@6CT depict that the superalkalis and alkali metals interact through the active cavity of 6CT. Interaction energies reveal that superalkalis have higher interaction with 6CT than alkali metals. The nonlinear optical (NLO) response of the reported complexes is estimated via both static and dynamic hyperpolarizabilities which are further rationalized by the HOMO–LUMO gap, natural bond orbital (NBO) charge transfer, dipole moment, polarizabilities and βvec. A remarkably high NLO response is computed for Na3O@6CT among all of the complexes. The static hyperpolarizability of the Na3O@6CT complex is 5 × 104 au along with the highest βvec value (2.5 × 104 au). High charge transfer (1.53e−) and small EH–L gap (2.96 eV) is responsible for such a large NLO response. For dynamic NLO responses, electro-optic Pockel's effect (EOPE) and second-harmonic generation (SHG) are explored. A very large quadratic nonlinear optical response (3.8 × 10−12 au) is observed for the Na3O@6CT complex. Moreover, the absorption spectrum of the Na3O@6CT complex shows ultra-high transparency in the ultraviolet and visible regions unlike any other of its counterparts.

Highlights

Signi cant consideration has been devoted to the fabrication of high performance nonlinear optical (NLO) materials,[1,2,3,4] due to their utility in electro-optic devices.[5,6,7]
A series of complexes have been designed by doping alkali metal atoms (Li, Na and K) and superalkalis (Li3O, Na3O & K3O) for nonlinear optical applications
The doping of alkali metals and their corresponding superalkalis leads to remarkably high NLO responses

Summary

Introduction

Signi cant consideration has been devoted to the fabrication of high performance nonlinear optical (NLO) materials,[1,2,3,4] due to their utility in electro-optic devices.[5,6,7] To ful l this demand, various kinds of novel NLO materials with excess electrons have been designed.[8,9] It is very well documented that the excess electrons play a pivotal role in the large NLO response.[10,11] Excess electrons can be generated by capping a material with alkali metal atoms.[12] alkali metal doping leads to large rst and second hyperpolarizabilities of the systems.[13,14] Munsif et al.,[15] reported the exceptionally high NLO response of inorganic nanocages upon doping with alkali metal atoms. The authors claimed that the hyperpolarizability of potassium doped boron phosphide (inorganic nanocage) was the highest (7.9 Â 105 au) ever reported. Maria and co-workers illustrated the exceptional increase in the hyperpolarizability of inorganic systems to 1.3 Â 104 au from 0.00 au (pure material) upon doping with potassium metal.[16] In

Methods

Results

Conclusion