Amorphous metal thin film electrode for mechanically robust charge collection of organic photovoltaics

Polymeric electrodes are known for their intrinsically high mechanical stability, which suggests that fabrication of highly flexible photovoltaic devices is feasible through the implementation of these soft materials. However, the metallic electrodes that provide an electrical connection to these soft polymers often cause the polymeric electrodes to become mechanically unstable, degrading the overall performance of flexible photovoltaic devices under external stress. In this research, for the first time, aluminum-yttrium (AlY) amorphous metallic alloy thin film functions as a charge collecting electrode for poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) polymeric electrodes as part of a flexible organic solar cell. Unlike conventional metals, amorphous metals consist of atoms without a long-range ordered structure, endowing them with robust mechanical strength and flexibility. Optical and electrical analyses revealed that an amorphous AlY metal thin film on a PEDOT:PSS electrode withstands cyclic bending stresses without any mechanical failure. The incorporation of an amorphous metal electrode resulted in improved stability of the electrical parameters and efficiency under cyclic bending stresses when compared to organic photovoltaic devices with conventional crystalline metallic electrodes. [Display omitted] •Amorphous metal alloy with AlY composition is firstly fabricated into electrodes for PEDOT:PSS.•Amorphous AlY thin film exhibits excellent mechanical stability during 1000 times bending.•OPV device with amorphous AlY reveals superior mechanical stability than that with crystalline Al.•Chemically inert interface between AlY and polymeric anode is advantageous for stable OPV operation.