Thermoelectric properties of Bi2O2Se single crystals

Abstract

Bismuth oxyselenide (Bi2O2Se) attracts great interest as a potential n-type complement to p-type thermoelectric oxides in practical applications. Previous investigations were generally focused on polycrystals. Here, we performed a study on the thermoelectric properties of Bi2O2Se single crystals. Our samples exhibit electron mobility as high as 250 cm2 V−1 s−1 and thermal conductivity as low as 2 W m−1 K−1 near room temperature. The maximized figure of merit is yielded to be 0.188 at 390 K, higher than that of polycrystals. Consequently, a rough estimation of the phonon mean free path (ℓph) from the kinetic model amounts to 12 Å at 390 K and follows a T−1 behavior. An extrapolation of ℓph to higher temperatures indicates that this system approaches the Ioffe–Regel limit at about 1100 K. In light of the phonon dispersions, we argue that the ultralow ℓph is attributed to intense anharmonic phonon–phonon scattering, including the Umklapp process and acoustic to optical phonon scattering. Our results suggest that single crystals provide a further improvement of thermoelectric performance of Bi2O2Se.

Effect of Hydrostatic Pressure on Lone Pair Activity and Phonon Transport in Bi2O2S

“…1−4 Similarly, layered structures promote strong bonding heterogeneity (a combination of rigid and fluctuating sublattices in a material) and have important implications for enhancing complex, interdependent thermoelectric properties, such as high power factor and low κ l . 5 Recently, dibismuth dioxychalcogenides, Bi 2 O 2 Ch (Ch = S, Se, Te), and their 2D counterparts 6−10 have garnered tremendous research interest due to their potential applications in thermoelectrics, 9,11,12 ferroelectrics, 13 and optoelectronics. 7,9,14−16 Bi 2 O 2 (Se/Te) crystallizes in the body-centered tetragonal (SG: I4/mmm, Z = 1 formula units (fu) per primitive cell) anti-ThCr 2 Si 2 -type structure, while Bi 2 O 2 S prefers to crystallize in the low-symmetry primitive orthorhombic structure (SG: Pnmn, Z = 2 fu) per primitive cell) due to the stereochemically active 6s 2 lone pair of Bi 3+ cations.…”

“…Recently, dibismuth dioxychalcogenides, Bi 2 O 2 Ch (Ch = S, Se, Te), and their 2D counterparts − have garnered tremendous research interest due to their potential applications in thermoelectrics, ,, ferroelectrics, and optoelectronics. ,,− Bi 2 O 2 (Se/Te) crystallizes in the body-centered tetragonal (SG: I 4/ mmm , Z = 1 formula units (fu) per primitive cell) anti-ThCr 2 Si 2 -type structure, while Bi 2 O 2 S prefers to crystallize in the low-symmetry primitive orthorhombic structure (SG: Pnmn , Z = 2 fu) per primitive cell) due to the stereochemically active 6s 2 lone pair of Bi 3+ cations. The stereochemically active lone pair creates a structural distortion, causing a material to crystallize in relatively low symmetry compared to materials with stereochemically inactive lone pairs. , The crystal structure of Bi 2 O 2 Ch consists of alternating Bi 2 O 2 and chalcogen (S/Se/Te) layers, which are held together by strong electrostatic forces , in contrast to van der Waals (vdW) interactions that are typically observed in layered materials. − Infrared, Raman spectra, and strain effects on bulk and monolayer Bi 2 O 2 Ch crystals have been systematically investigated to explore their possible applications in nanoelectronics …”

Bi2O2Te Nanosheets Saturable Absorber‐Based Passive Mode‐Locked Fiber Laser: From Soliton Molecules to Harmonic Soliton

“…[13,14] Thereafter, extensive investigations are carried out with focus on the physical and chemical properties, which reveals its outstanding thermoelectric properties, sensible photon response, adjustable bandgap, ultra-fast carrier mobility, and long carrier relaxation time. [11,[15][16][17] The combination of these properties renders it a promising candidate for various novel optoelectronic devices at the near-infrared (NIR) and mid-infrared (mid-IR) regions. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] Recently, bismuth oxytelluride (Bi 2 O 2 Te), as a new addition to the bismuth oxychalcogenide family, has attracted increasing research attention.…”

“…[ 13,14 ] Thereafter, extensive investigations are carried out with focus on the physical and chemical properties, which reveals its outstanding thermoelectric properties, sensible photon response, adjustable bandgap, ultra‐fast carrier mobility, and long carrier relaxation time. [ 11,15–17 ] The combination of these properties renders it a promising candidate for various novel optoelectronic devices at the near‐infrared (NIR) and mid‐infrared (mid‐IR) regions. [ 18–32 ]…”

Thermoelectric Properties of Cu-added Polycrystalline Bi2O2Se Oxyselenide

“…Bi 2 O 2 Se has a large S and intrinsically low thermal conductivity; however, because of its low carrier concentration and σ, the thermoelectric performance of Bi 2 O 2 Se is limited [13]. Recent studies have been conducted to improve the electrical transport properties of Bi 2 O 2 Se by various strategies, such as anion doping, cation doping, Ag addition, and Bi deficiency [14][15][16][17][18][19].…”