2D Ca₃Sn₂S₇ Chalcogenide Perovskite: A Graphene‐Like Semiconductor with Direct Bandgap 0.5 eV and Ultrahigh Carrier Mobility 6.7 × 10⁴ cm² V⁻¹ s⁻¹

Abstract

Graphene, a star 2D material, has attracted much attention because of its unique properties including linear electronic dispersion, massless carriers, and ultrahigh carrier mobility (104–105 cm2 V−1 s−1). However, its zero bandgap greatly impedes its application in the semiconductor industry. Opening the zero bandgap has become an unresolved worldwide problem. Here, a novel and stable 2D Ruddlesden–Popper‐type layered chalcogenide perovskite semiconductor Ca3Sn2S7 is found based on first‐principles GW calculations, which exhibits excellent electronic, optical, and transport properties, as well as soft and isotropic mechanical characteristics. Surprisingly, it has a graphene‐like linear electronic dispersion, small carrier effective mass (0.04 m0), ultrahigh room‐temperature carrier mobility (6.7 × 104 cm2 V−1 s−1), Fermi velocity (3 × 105 m s−1), and optical absorption coefficient (105 cm−1). Particularly, it has a direct quasi‐particle bandgap of 0.5 eV, which realizes the dream of opening the graphene bandgap in a new way. These results guarantee its application in infrared optoelectronic and high‐speed electronic devices.

Ultrahigh Carrier Mobility in the Two-Dimensional Semiconductors B8Si4, B8Ge4, and B8Sn4

“…Notably, the hole mobility of 1.6 × 10 6 cm 2 V −1 s −1 in the xdirection even exceeds the reported values of graphene (2 × 10 5 cm 2 V −1 s −1 ), 4 graphdiyne (2 × 10 5 cm 2 V −1 s −1 ), 44 and 2D Ca 3 Sn 2 S 7 (6.7 × 10 4 cm 2 V −1 s −1 ). 45 The lower deformation potential constants in the x-than the y-direction again are explained by Table 2. Similar to B 8 Si 4 and B 8 Ge 4 , the VBM of B 8 Sn 4 is dominated by p y states (B c and Sn, but not B l ).…”

Ti-Alloying of BaZrS3 Chalcogenide Perovskite for Photovoltaics

“… 23 Another recent theoretical paper predicted that two-dimensional (2D) Ca 3 Sn 2 S 7 possess a graphene-like linear electronic dispersion with a direct band gap and ultrahigh carrier mobility comparable to that of graphene. 24 …”

Realizing High Electrical Conductivity in Chlorine-Doped Bi2S3 Thermoelectric Thin Films via Air Plasma Treatment

“…Therefore, impurity states generated near the Fermi level, which facilitated impurity ionization and introduced more carriers, enhanced the conductivity in Bi 2 S 3 Figure S9 displays the difference in the charge density distribution diagram of Bi 10 S 14 Cl (corresponding to the (001) lattice plane), along with the corresponding electron localized functions (ELF) values …”