Femtosecond nonlinear optical response and minority carrier lifetime of F4TCNQ-doped bismuthene for optoelectronic and ultrafast photonic applications

Abstract

Bismuthene has received a lot of interest because of its unusual electronic and photonic properties. To widen the use of bismuthene in optoelectronic and ultrafast photonic devices, its electronic and optical characteristics should be tuned. Herein, for the first time, a strong p-type molecular dopant, such as tetrafluoro-tetracyanoquinodimethane (F4TCNQ), is used to achieve efficient surface charge transfer doping (SCTD) of bismuthene. The minority carrier lifetime measurements of bismuthene shifted to 6.5 µs after doping, confirming that F4TCNQ has the opportunity to boost bismuthene's p-type conductivity due to an unusual charge transfer interaction between bismuthene and F4TCNQ molecules. The thermally generated intermolecular charge transfer influence between bismuthene and F4TCNQ resulted in an improved nonlinear optical and optical limiting response, which was estimated by femtosecond z-scan measurements. Our findings suggest that SCTD is an appropriate means for tuning the linear and nonlinear optical properties of bismuthene via modulating their band gap and minority carrier lifetime. This alternating approach expands its potential in electronic, optoelectronic, and ultrafast photonic devices.