Exploitation of Improved Long‐Term Stability and Enhanced Photoconversion Efficiency of Organic Photovoltaics Using Flexible Transparent Conducting Electrode with Dual Functions of Antireflection and Ultrahigh Moisture Barrier

Abstract

A structure of flexible glass/flexible transparent conducting electrode (TCE) comparable with the conventional glass/indium tin oxide (ITO) substrate is proposed by combining an Ag NW + PEDOT:PSS hybrid TCE (h‐TCE) with triple‐layer a‐SiNx:H/n‐SiOxNy/h‐SiOx ultrahigh barrier (UHB) films. The UHB films have dual functions of both moisture barriers with a water vapor transmission rate (WVTR) of 1.6 × 10−5 × g m−2 day−1 and antireflection (AR) with a gradient refractive index. Flexible PTB7:PC70BM‐based organic photovoltaics (OPVs) with the AR‐UHB film achieve a maximum power conversion efficiency (PCE) of ηmax = 8.33%, saturation current density (Jsc) of 17.67 mA cm−2, and external quantum efficiency (EQE) of 63.3%, which are higher than ηmax = 7.63%, Jsc = 15.25 mA cm−2, and EQE = 59.26% of the OPVs on glass/ITO. These result from the increase in the absorption of the donor PTB7 due to the AR effect of the UHB films. A long‐term stability of the AR‐UHB encapsulation layer in damp heat (40 °C/85% relative humidity [RH]) is confirmed by the result that the measured T80 and T50 values for the OPV device on glass/ITO encapsulated with the AR‐UHB film are about 1008 h (42 days) and 2205 h (92 days), respectively.