Enhanced solar water oxidation and unassisted water splitting using graphite-protected bulk heterojunction organic photoactive layers
Mátyás Dabóczi, Flurin Eisner, Joel Luke, Shi Wei Yuan, Noof Al Lawati, Maoqing Zhi, Mengya Yang, Jolanda Simone Müller, Katherine Stewart, Ji‐Seon Kim, Jenny Nelson, Salvador Eslava
Abstract
Abstract Polymer donors and non-fullerene acceptors have played an important role as photoactive materials in the development of high-efficiency organic solar cells and have immense potential in devices for direct solar hydrogen generation. However, their use in direct solar water-splitting devices has been limited by their instability in aqueous environment and recombination losses at the interface with catalysts. Here we report anodes containing PM6:D18:L8-BO photoactive layers reaching high solar water oxidation photocurrent density over 25 mA cm −2 at +1.23 V versus reversible hydrogen electrode and days-long operational stability. This was achieved by integrating the organic photoactive layer with a graphite sheet functionalized with earth-abundant NiFeOOH water oxidation catalyst, which provides both water resistance and electrical connection between the catalyst and the photoactive layer without any losses. Using monolithic tandem anodes containing organic PM6:D18:L8-BO and PTQ10:GS-ISO photoactive layers, we achieve a solar-to-hydrogen efficiency of 5%. These results pave the way towards high-efficiency, stable and unassisted solar hydrogen generation by low-cost organic photoactive materials.