p‐Type Near‐Infrared Transparent Delafossite Thin Films with Ultrahigh Conductivity

Abstract

modulation of the valence band" (CMVB), and the delafossite CuAlO 2 was got the nod as p-type TC thin films. [1] Subsequently, the Cu-based delafossite oxides (CuMO 2 , M = Cr, B, Ga, Sc, Y, etc.) are extensively studied in the field of p-type TC thin films. [9][10][11][12][13][14] In particular, the high optical transparency of CuMO 2 thin films in the near-infrared (NIR, 750 to 2400 nm) spectrum is potentially utilized in emerging NIR TC applications, such as solar cells, infrared imaging and emission devices, and fiber-optic communications operating at 1550 nm. [11,15,16] High conductivity p-type oxides are unavailable since the upper edge of valence band (VB) is composed of strongly localized oxygen 2p orbitals. [17][18][19] The design for mitigating the localization behavior is to extend the VB structure by introducing covalency in the metal-oxygen bonding, namely CMVB. [1] For delafossite CuMO 2 oxides, the cationic Cu + has a closed shell 3d 10 electron configuration, in which the energy level is almost close to the oxygen 2p levels. The tetrahedral coordination of oxide ions will prompt the outermost eight electrons coordinate with the cations. Therefore, more covalent bonds and hybridization levels between Cu 3d 10 and O 2p 6 are introduced, resulting in a large dispersion and reduction of the localization behavior for the VB. [20] However, previously Design and implementation of efficient p-type transparent conducting (TC) oxides with excellent performance are the global material challenge. The strategy of "chemical modulation of the valence band" triggers the enthusiasm for p-type TC delafossite CuMO 2 . However, the low conductivity of previous CuMO 2 films obstructs the development of delafossite-based electronics. Herein, a new p-type 4d transition metal Rh-based CuRhO 2 film with large-size is first designed and fabricated by a facile solution method. Roomtemperature conductivity as high as 735 S cm −1 is achieved by substituting 10%Mg in Rh sites. Additionally, the acceptor-doped CuRhO 2 films exhibit high near-infrared transmittance of 85-60% with low room-temperature sheet resistance of 4.28-0.18 kΩ sq −1 . Furthermore, the electronic structure, electrical transport mechanism, and intra-band excitation feature for the CuRhO 2 film are unveiled. The theoretical and experimental results make a great advance in p-type TC films and will pave a promising blueprint for future multifunctional opto-electronic devices.

Unveiling the physical mechanisms driving delafossite crystal (ABX2) formation through interpretable machine learning

“…Delafossite crystal materials have gained significant attention in recent years due to their unique properties, rendering them suitable for various applications, such as transparent conducting oxides, 1,2 thermoelectric materials, 3 photoelectric conversion, 4,5 multiphase catalysis, 6–8 and biomedicine. 9–11 Delafossite crystals are ternary compounds with the generalized formula ABX 2 , characterized by alternating layers of edge-sharing BX 6 octahedra and A elements.…”