High Thermal Stability of Ultrathin‐Film Silver Transparent Electrodes for Over 100 cm ² Flexible Organic Photovoltaic Modules

ABSTRACT Thermal stability issue of ultrathin (< 10 nm) silver (Ag) transparent electrodes limit their applications for large‐area flexible organic photovoltaics (OPVs). In this work, we address this issue by developing a vacuum‐deposited tin oxide (SnO ₂ (evap.), 1 nm) seed layer for growing an ultrathin Ag transparent electrode. The 4 nm Ag transparent electrode grown on SnO ₂ (evap.) surface could withstand temperature as high as 250°C–300°C in air without any protection layer, which showed much higher thermal robustness than Ag films (4 nm) grown on other surfaces, including glass, polyethyleneimine, gold, nickel, chromium, copper, tungsten oxide, molybdenum oxide, and SnO ₂ (atomic layer deposition, ALD). The high thermal robustness and high optoelectronic properties of the ultrathin Ag film grown on SnO ₂ (evap.) are likely attributed to interfacial Sn–O–Ag chemical linkages. Based on the thin Ag/SnO ₂ (evap.) transparent electrodes, a flexible OPV module with an active area of 108 cm ² exhibits a PCE of 13.51%. Outdoor operational stability of the flexible module was further conducted via maximum power output point (MPP) tracking. After over one‐month outdoor tracking, the flexible OPV module showed high operational stability comparable to the silicon reference device. The flexible OPV module displayed higher power output than silicon reference devices under dim illumination.