Ultrathin Ag electrodes with an interfacial anchoring growth layer for flexible organic light-emitting devices

Ultrathin Ag electrodes with the low sheet resistance and high optical transmittance are the candidates for applications in flexible optoelectronic devices. However, the fabrication of ultrathin Ag electrodes with excellent optoelectrical properties and mechanical stability is challenging due to the fact that the ultrathin Ag layer obeys the Volmer-Weber growth mode when the Ag layer is too thin (<10 nm). In this paper, serine (Ser)-mediated anchoring the growth of ultrathin Ag films was proposed by the chemical bonding interactions between the group of -OH in Ser and Ag atoms. The composite transparent electrode of polyethylene terephthalate (PET)/Ser/Ag (7 nm)/MoO₃ (20 nm) possesses a low sheet resistance of ∼8.5 Ω/sq, a high optical transmittance of ∼87.2 % at 550 nm and the robust mechanical stability of 100,000 bending cycles at a bending radius of 5 mm. The excellent performance can be attributed to the formation of Ag-O bonds during the growth procedure of Ag films, resulting in the uniform growth of Ag films and outstanding adhesion to substrates. Flexible organic light-emitting devices were constructed based on the composite transparent electrodes, achieving a maximum luminance of ∼14070 cd/m² and a maximum current efficiency of ∼7.5 cd/A.