Significance We have developed ultraflexible 3-µm-thick organic photovoltaics (OPVs) with good environmental stability and a high efficiency of over 13% by a simple postannealing process. By combining the stable polymer donor/nonfullerene small molecule acceptor blends and thermally stabilized interfaces due to doping, our OPVs achieve extremely long shelf lifetime with an estimated value of over 11.4 y. A laboratory-scale OPV module is fabricated with a sufficiently high efficiency of 11.4%, total area of 2.04 cm ² , and a maximum power per unit weight of 9.90 W/g, showing a promising future for flexible OPVs as power sources for wearable electronics and soft robotics.