Room Temperature Processed Amorphous Sn-Excess-ITO Electrodes for High Performance Perovskite Light-Emitting Diodes

Achieving high efficiency perovskite light-emitting diodes (PeLEDs) requires transparent electrodes that combine low sheet resistance, high optical transmittance, and atomically smooth morphology. Conventional crystalline indium tin oxide (ITO) electrodes, however, necessitate high-temperature deposition above 300°C or post-annealing, resulting in grain boundaries and rough surfaces that are incompatible with flexible substrates and low-temperature device architecture. Here, we report room-temperature processed, grain boundary-free Sn excess doped indium tin oxide (SE-ITO) electrodes fabricated via RF-RF co-sputtering of In₂O₃ and SnO₂. Through the heavy incorporation Sn⁴⁺ dopants (19 wt.%) and optimized oxygen-vacancy engineering, the amorphous SE-ITO achieves an exceptional combination of low sheet resistance (10 Ω sq^-1) and high visible transmittance (85%), comparable to thermally annealed crystalline ITO. When implemented as the transparent anodes in green PeLEDs, the amorphous SE-ITO films enable a peak external quantum efficiency of 17.5% and a maximum luminance of 1860 cd m^-2, outperforming devices using commercial crystalline ITO (16.3%, 1690 cd m^-2). These results establish fully amorphous, room-temperature SE-ITO electrodes as a viable alternative to crystalline counterparts, offering a new pathway toward flexible, high-efficiency, and thermally compatible PeLED technologies.