Oxidized Black Phosphorene Gas Detector
What works for phosphorene, should work for bismuthene. Yes, that’s a word.
Bandgap Engineering of Phosphorene by Laser Oxidation toward Functional 2D Materials, Junpeng Lu, Jing Wu, Alexandra Carvalho, Angelo Ziletti, Hongwei Liu, Junyou Tan, Yifan Chen, A. H. Castro Neto, Barbaros Özyilmaz and Chorng Haur Sow, ACS Nano (12 September 2015), DOI: 10.1021/acsnano.5b04623
We demonstrate a straightforward and effective laser pruning approach to reduce multilayer black phosphorus (BP) to few-layer BP under ambient condition. Phosphorene oxides and suboxides are formed and the degree of laser-induced oxidation is controlled by the laser power. Since the band gaps of the phosphorene suboxide depend on the oxygen concentration, this simple technique is able to realize localized band gap engineering of the thin BP. Micropatterns of few-layer phosphorene suboxide flakes with unique optical and fluorescence properties are created. Remarkably, some of these suboxide flakes display long-term (up to 2 weeks) stability in ambient condition. Comparing against the optical properties predicted by first-principle calculations, we develop a “calibration” map in using focused laser power as a handle to tune the band gap of the BP suboxide flake. Moreover, the surface of the laser patterned region is altered to be sensitive to toxic gas by way of fluorescence contrast. Therefore, the multicolored display is further demonstrated as a toxic gas monitor. In addition, the BP suboxide flake is demonstrated to exhibit higher drain current modulation and mobility comparable to that of the pristine BP in the electronic application.
I am making steady day by day progress on my chosen problem, apparently.
Remember, I need to have this wrapped up by October 8th.
Oh, and behold the Phosphoronics revolution!
Phosphonics. That’s a word too!
For some background on phosphorene oxidation dynamics:
Intrinsic Defects, Fluctuations of the Local Shape, and the Photo-Oxidation of Black Phosphorus, Kainen L. Utt, Pablo Rivero, Mehrshad Mehboudi, Edmund O. Harriss, Mario F. Borunda, Alejandro A. Pacheco SanJuan and Salvador Barraza-Lopez, ACS Cent. Sci. (6 August 2015), DOI: 10.1021/acscentsci.5b00244
Intrinsic defects induce fluctuations of a local shape. The energy barrier for oxygen dimers to pierce black phosphorus reduces its magnitude there within the realm of light-induced excitations. Defects dissociate oxygen dimers too.
Black phosphorus is a monatomic semiconducting layered material that degrades exothermically in the presence of light and ambient contaminants. Its degradation dynamics remain largely unknown. Even before degradation, local-probe studies indicate non-negligible local curvature—through a nonconstant height distribution—due to the unavoidable presence of intrinsic defects. We establish that these intrinsic defects are photo-oxidation sites because they lower the chemisorption barrier of ideal black phosphorus (> 10 eV and out of visible-range light excitations) right into the visible and ultraviolet range (1.6 to 6.8 eV), thus enabling photoinduced oxidation and dissociation of oxygen dimers. A full characterization of the material’s shape and of its electronic properties at the early stages of the oxidation process is presented as well. This study thus provides fundamental insights into the degradation dynamics of this novel layered material.