Ba3.5Cu7.55In1.15Se9: A Wide-Bandgap Copper Indium Selenide Reveals Strong Luminescence and Third-Harmonic Generation

초록

A new copper indium selenide, Ba3.5Cu7.55In1.15Se9, was synthesized by the KBr flux reaction at 800 degrees C. The compound crystallizes with orthorhombic Pnma, a = 46.1700(12) angstrom, b = 4.26710(10) angstrom, c = 19.8125(5) angstrom, and Z = 8. The structural framework mainly consists of four sites of cubane-type defective M4Se3 (M = Cu, Cu/In) units with disordered Cu+/In3+ ions present at the part corner of each unit. The single crystal emits intense photoluminescence at 657 nm with a relative quantum yield (RQY) 0.2 times that of rhodamine 6G powder. The compound belongs to a direct band gap at 1.91 eV, analyzed by Tauc's plot, and the energy is close to the PL position. The Hall effect measurement on a pressed pellet reveals an n-type conductivity with a carrier concentration of 3.358 x 10(17) cm(-3) and a mobility of 24.331 cm(2) V-1 s(-1). Furthermore, the compound produces a strong nonlinear third-harmonic generation (THG), with an chi((3))(S) value of 1.3 x 10(5) pm(2)/V-2 comparable to 1.6 x 10(5) pm(2)/V-2 for AgGaSe2 measured at 800 nm.

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