Strain modulating electronic band gaps and SQ efficiencies of semiconductor 2D PdQ(2) (Q = S, Se) monolayer

We studied the physical, electronic transport and optical properties of a unique pentagonal PdQ(2) (Q = S, Se) monolayers. The dynamic stability of 2Dwrinkle like-PdQ(2) is proven by positive phonon frequencies in the phonon dispersion curve. The optimized structural parameters of wrinkled pentagonal PdQ(2) are in good agreement with the available experimental results. The ultimate tensile strength (UTHS) was calculated and found that, penta-PdS(2) monolayer can withstand up to 16% (18%) strain along x (y) direction with 3.44 GPa (3.43 GPa). While, penta-PdSe(2) monolayer can withstand up to 17% (19%) strain along x (y) dirrection with 3.46 GPa (3.40 GPa). It is found that, the penta-PdQ(2) monolayers has the semiconducting behavior with indirect band gap of 0.94 and 1.26 eV for 2D-PdS(2) and 2D-PdSe(2), respectively. More interestingly, at room temperacture, the hole mobilty (electron mobility) obtained for 2D-PdS(2) and PdSe(2) are 67.43 (258.06) cm(2) V(−1) s(−1) and 1518.81 (442.49) cm(2) V(−1) s(−1), respectively. In addition, I-V characteristics of PdSe(2) monolayer show strong negative differential conductance (NDC) region near the 3.57 V. The Shockly-Queisser (SQ) effeciency prameters of PdQ(2) monolayers are also explored and the highest SQ efficeinciy obtained for PdS(2) is 33.93% at −5% strain and for PdSe(2) is 33.94% at −2% strain. The penta-PdQ(2) exhibits high optical absorption intensity in the UV region, up to 4.04 × 10(5) (for PdS(2)) and 5.28 × 10(5) (for PdSe(2)), which is suitable for applications in optoelectronic devices. Thus, the ultrathin PdQ(2) monolayers could be potential material for next-generation solar-cell applications and high performance nanodevices.