Mixed‐Addenda Dawson‐Type Polyoxometalates as High‐Performance Anode Interlayer Materials for Efficient Organic Optoelectronic Devices

Abstract Electrode interlayer plays a pivotal role in the performance enhancement of optoelectronic devices. At present, poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and molybdenum oxide are the two most popular anode interlayer (AIL) materials in organic optoelectronic devices, but both of them have obvious drawbacks in practical use. Owing to the lack of suitable semiconductor with suitable energy level, the development of AIL materials as alternatives to PEDOT:PSS and MoO 3 remains a challenge. Herein, a series of Dawson‐type polyoxometalates (POMs) is synthesized with tunable chemical compositions and photoelectronic properties to develop efficient AILs for organic optoelectronic devices of organic light‐emitting diode (OLED) and organic solar cell (OSC). The POM films exhibit a high work function, excellent conductivity, good optical transmittance, and smooth surface, endowing the POM AILs with outstanding hole injection/collection abilities. The high performance of Dawson‐type POMs in hole injection/collection ensures an efficient hole transfer from the organic layer to the anode, depressing the charge recombination in the optoelectronic devices. The OSCs modified by POM4 exhibit 17.8% and 16.1% power conversion efficiencies with an active area of 0.04 and 1.00 cm 2 , respectively. The OLEDs with POM3 and POM4 exhibit remarkably superior luminous efficiency to the PEDOT:PSS device, along with a significantly reduced turn‐on voltage from 3.8 to 2.8 V.