Transparent conducting oxides (TCOs) are increasingly critical components in photovoltaic cells, low‐e windows, flat panel displays, electrochromic devices, and flexible electronics. The conventional TCOs, such as Sn‐doped In 2 O 3 , are crystalline single phase materials. Here, we report on In‐Zn‐O (IZO), a compositionally tunable amorphous TCO with some significantly improved properties. Compositionally graded thin film samples were deposited by co‐sputtering from separate In 2 O 3 and ZnO targets onto glass substrates at 100 °C. For the metals composition range of 55–84 cation% indium, the as‐deposited IZO thin films are amorphous, smooth ( R RMS < 0.4 nm), conductive ( σ ∼ 3000 Ω −1 · cm −1 ), and transparent in the visible ( T Vis > 90%). Furthermore, the amorphous IZO thin films demonstrate remarkable functional and structural stability with respect to heating up to 600 °C in either air or argon. Hence, though not completely understood at present, these amorphous materials constitute a new class of fundamentally interesting and technologically important high performance transparent conductors.

High-throughput combinatorial approaches have been used for the discovery and optimization of transparent conducting oxide (TCO) materials for PV applications. We report on current investigations in In-Zn-O, In-Ti-O and In-Mo-O systems. The InZnO system is shown to be amorphous in the best conducting range with a conductivity of ~ 3000 Ω-cm-1 for 50%-70% In/Zn. The amorphous InZnO films are very smooth (2..ANG.. rms). In-Ti-O is found to be an excellent high-mobility TCO with mobilities of greater than 80 cm2/v-sec and conductivities of more than 6000 Ω-cm-1 for sputtered thin film materials.

Indium-zinc-oxide (IZO) compositional libraries were deposited with dc magnetron sputtering onto glass substrates at 100 degreesC and analysed with high throughput, combinatorial techniques. The composition range from 4 to 95 at% In for Zn was explored. A peak in conductivity with delta > 3000 (Omega cm)(-1) was observed at an indium content of similar to70%. The mobility exceeded 30 cm(2) (V s)(-1) and the carrier concentrations were greater than 8 x 10(20) cm(-3). Crystalline phases were observed for In concentrations less than 45% and greater than 80% with an intermediate amorphous region. The low indium content films have a zinc oxide type structure with a ZnO (002) spacing ranging from similar to2.61 to 2.85 Angstrom for 4% In and 45% In, respectively. For indium contents between 82% and 95%, the In2O3 (222) spacing varied from 2.98 to 2.99 Angstrom. Regardless of the composition or the degree of crystallinity, all films showed high optical transparency with the transmission > 80% across the visible spectrum.