A long-term stability test showcased the potential of OPV-BiVO4 tandem devices towards practical fuel synthesis, producing 28.9 µmol cm -2 H2 (37.7% FY), 27.0 µmol cm -2 CO (35.2% FY) and 27.6 µmol cm -2 O2 (71.8% FY) over 96 h CA. A gradual photocurrent decay was observed during the 4-day test (Fig. ), which follows a similar trend to OPV photocathodes (Fig. ). Accordingly, this effect was caused by a gradual decrease in OPV photovoltage affecting the photoelectrode overlap. All tandems sustained a (CO+H2):O2 product ratio of around 2:1, with slight deviations due to O2 reduction on the cathodic side, bubble trapping, instrumental sensitivity near the detection limit, or cell leakage, whereas the O2 signal became gradually more noisy due to water condensation on the tip of the fluorescence sensor (Fig. -e and Supplementary Video). The early onset potentials, high photocurrent density, and long-term operation demonstrated in this work highlight OPV photoelectrodes as a strong alternative towards practical solar fuel synthesis. To this end, our system takes advantage of a carefully designed device structure including a fullerene-free bulk heterojunction and charge selective layers, which provide a significant photocurrent improvement over the tens of µA cm -2 originally reported for π-conjugated polymers (Supplementary Table ). This device architecture provides a 1 V photovoltage, which matches those of state-of-the-art organic and even inorganic photoelectrodes. The introduction of a GE encapsulant further enables a leap in stability over previous studies involving nanometre thin TiO2, PEI or Pt protective layers. The 0.5-1 mm thick hydrophobic coating avoids pinholes and cross-plane moisture infiltration, whereas polymer interactions between PCE10 and the epoxy resin produce a tight seal around the sample edges, preventing the lateral moisture degradation observed in perovskite photocathodes. While a gradual photocurrent decay is consistent with photovoltaic reports, the molecular tuneability of OSCs in terms of synthesis, functionalisation and donor-acceptor combinations presents a wide scope for further performance improvements.