Two-Dimensional Boron Carbon Oxynitride Nanosheets and Porphyrin Hybrid: A Promising Material for Optical Limitingand Optoelectronic Applications

Next-generation multifunctional optoelectronic devices demand miniaturization, efficiency, and tunability, driving the exploration of novel material platforms. Two-dimensional (2D) materials and their functionalization offer tailored and unprecedented electronic, optical, and mechanical properties. Among the diverse family of 2D materials, boron carbon oxynitride (BCNO) stands out due to its strong UV to visible-range absorption. However, its functionalization remains largely unexplored despite its inherent ability to host electrostatic, π–π, and hydrogen-bonding interactions. In this work, we report on the functionalization of 2D BCNO nanosheets with porphyrin (TSPP), a molecule offering strong donor–acceptor interactions. The resulting 2D BCNO–TSPP hybrid exhibits an efficient interfacial nonradiative excitation-energy transfer, facilitated by the spectral overlap between 2D-BCNO emission and TSPP absorption, resulting in pronounced photoluminescence modulation. This hybrid demonstrates a 2-fold enhancement in photocurrent and an attractive low optical limiting threshold of 176 μJ/cm2 under 400 nm excitation using 200 fs pulses, attributed to strong reverse saturable absorption. This represents a significant improvement compared to the limiting thresholds of 2D BCNO (300 μJ/cm2) and TSPP (260 μJ/cm2), highlighting the prominent enhancement in the hybrid. Addition of different concentrations of TSPP to 2D BCNO through the ultrasonication process leads to a pronounced photoluminescence quenching accompanied by a red shift in the emission band. This tunable emission, combined with the increased absorption centers introduced by TSPP, further strengthens the optical limiting response. Together, these multifunctional properties establish the 2D BCNO–TSPP hybrid as a promising platform for future advanced optoelectronic devices.