Madas S, Mishra S K, Kahaly S, Kahaly M Upadhyay
ELI-ALPS, ELI-HU Non-Profit Ltd., Dugonics ter 13, Szeged, 6720, Hungary.
Physical Research Laboratory (PRL), Navrangpura, Ahmedabad, 380009, India.
Sci Rep. 2019 Jul 16;9(1):10307. doi: 10.1038/s41598-019-44823-x.
This work demonstrates that black phosphorene, a two dimensional allotrope of phosphorus, has the potential to be an efficient photo-thermionic emitter. To investigate and understand the novel aspects we use a combined approach in which ab initio quantum simulation tools are utilized along with semiclassical description for the emission process. First by using density functional theory based formalism, we study the band structure of phosphorene. From the locations of electronic bands, and band edges, we estimate the Fermi level and work function. This leads us to define a valid material specific parameter space and establish a formalism for estimating thermionic electron emission current from phosphorene. Finally we demonstrate how the emission current can be enhanced substantially under the effect of photon irradiation. We observe that photoemission flux to strongly dominate over its coexisting counterpart thermionic emission flux. Anisotropy in phosphorene structure plays important role in enhancing the flux. The approach which is valid over a much wider range of parameters is successfully tested against recently performed experiments in a different context. The results open up a new possibility for application of phosphorene based thermionic and photo-thermionic energy converters.
这项工作表明，黑磷烯这种磷的二维同素异形体，有潜力成为一种高效的光热电子发射体。为了研究和理解这些新特性，我们采用了一种组合方法，其中使用了从头算量子模拟工具以及对发射过程的半经典描述。首先，通过基于密度泛函理论的形式体系，我们研究了磷烯的能带结构。从电子能带的位置和带边，我们估计了费米能级和功函数。这使我们能够定义一个有效的材料特定参数空间，并建立一种从磷烯估计热电子发射电流的形式体系。最后，我们展示了在光子辐照的作用下，发射电流如何能大幅增强。我们观察到光发射通量比其共存的热电子发射通量占主导得多。磷烯结构中的各向异性在增强通量方面起着重要作用。这种在更广泛参数范围内有效的方法，已针对近期在不同背景下进行的实验成功进行了测试。这些结果为基于磷烯的热电子和光热电子能量转换器的应用开辟了新的可能性。
