Surface engineering of two-dimensional hexagonal boron-nitride for optoelectronic devices

Two-dimensional hexagonal boron nitride (2D h-BN) is being extensively studied in optoelectronic devices due to its electronic and photonic properties. However, the controlled optimization of h-BN's insulating properties is necessary to fully explore its potential in energy conversion and storage devices. In this work, we engineered the surface of h-BN nanoflakes via one-step in situ chemical functionalization using a liquid-phase exfoliation approach. The functionalized h-BN (F-h-BN) nanoflakes were subsequently dispersed on the surface of TiO2 to tune the TiO2/QDs interface of the optoelectronic device. The photoelectrochemical (PEC) devices based on TiO2/F-h-BN/QDs with optimized addition of carbon nanotubes (CNTs) and scattering layers showed 46% improvement compared to the control device (TiO2/QDs). This significant improvement is attributed to the reduced trap/carrier recombination and enhanced carrier injection rate of the TiO2-CNTs/F-h-BN/QDs photoanode. Furthermore, by employing an optimized TiO2-CNTs/F-h-BN/QDs photoanode, QDs-sensitized solar cells (QDSCs) yield an 18% improvement in photoconversion efficiency. This represents a potential and adaptability of our approach, and pathway to explore surface-engineered 2D materials to optimize the interface of solar energy conversion and other emerging optoelectronic devices. The photoelectrochemical devices based on TiO2-CNTs/F-h-BN/QDs yield a 46% improvement compared to the control device (TiO2/QDs) due to reduced trap and associated non-radiative carrier recombination.