A promising two-dimensional solar cell donor: Black arsenic–phosphorus monolayer with 1.54 eV direct bandgap and mobility exceeding 14,000 cm2V−1s−1

Abstract

Excitonic solar cells (XSCs) have attracted tremendous attentions due to their high solar-to-electric power conversion efficiency (PCE). However, to further improve the PCE of XSC, finding an efficient donor material with both suitable direct bandgap and high carrier mobility is still a great challenge. Here, we report a black arsenic-phosphorus monolayer as highly efficient donor for XSCs based on first-principle calculations. Firstly, monolayer arsenic-phosphorus polymorphs with α, β, γ, δ, and ε phases were built, among which α−AsP and β−AsP have been verified to be thermodynamically stable. Significantly, monolayer α−AsP possesses a direct bandgap with energy of 1.54 eV, which covers the main energy of solar spectrum. Moreover, its electronic mobility is as high as 14,380 cm 2 V-1 s-1 , which is much higher than silicon. These two crucial merits made it a promising candidate as donor materials for XSC device and the theoretical simulations demonstrate a maximum PCE of 22.1% for the primarily designed α−AsP/GaN XSC. Interestingly, the suitable electronic structure of α−AsP enables a formation of perfect type-II semiconductor heterojunction with GaN, which will boost the separation and transport of photogenerated carriers with the assistance of built-in field and high mobility. Particularly, α phase few-layer material of arsenic-phosphorus alloy has been experimentally synthesized recently, which paves the way for experimental realization of black arsenic-phosphorus monolayer donor.

Small strain induced large piezoelectric coefficient in α-AsP monolayer

“…To confirm studied materials to be semiconductors at ap-plied strain, the GGA gaps as a function of strain for α-AsP monolayer along the armchair direction and the zigzag direction, β-AsP monolayer and SnSe monolayer along the armchair direction are plotted in Figure 8. Our calculated unstrained gaps for monolayer α-AsP (0.90 eV), β-AsP (1.76 eV) and SnSe (0.93 eV) agree well with previous theoretical values 27,37 . It is clearly seen that, in considered strain range, all studied 2D materials have a band gap.…”

“…The optimized lattice constants a=b=3.44Å for β-AsP, which agrees well with previous values 12,27 . The calculated elastic stiffness coefficients C ij and piezoelectric tensors e/d ij are shown in Table II, along with available calculated values 12 .…”

“…Firstly, the lattice constants of α-AsP are optimized, and the corresponding a=3.50Å and b=4.70Å, which agree well with previous calculated values 12,27 . To determine the piezoelectric strain tensors d ij , we first calculate the elastic stiffness coefficients C ij and piezoelectric stress tensors e ij , and then d ij can be attained.…”

Black Phosphorus: Synthesis and Application for Solar Cells

“…In particular, emerging PV technologies based on excitonic semiconducting materials, dye sensitizers, organic compounds, perovskite crystals, heterojunction interfaces, and QDs have received intense attention in the past few decades. [44][45][46][47][48][49] These computational studies have suggested that the BP derivatives might be ideally suited for building high-efficiency and low-cost solar cells. [43] Phosphorene possesses fascinating properties such as a thickness-dependent bandgap, excellent carrier mobility, and ambipolar conduction characteristics.…”

Anisotropic In‐Plane Ballistic Transport in Monolayer Black Arsenic‐Phosphorus FETs

“…Recently, a new family of 2D binary materials based on group‐V such as black arsenic‐phosphorus (AsP) has emerged as an attractive candidate for optoelectronic applications because it possesses a tunable narrow bandgap and exhibits excellent in‐plane anisotropic photoresponses 24–26. However, in‐depth transport studies of its potential performance in integrated circuits are currently absent from the field, especially when channel length is scaled down sub‐10 nm.…”