Enhanced solar water oxidation and unassisted water splitting using graphite-protected bulk heterojunction organic photoactive layers

Dabóczi, Mátyás and Eisner, Flurin and Luke, Joel and Yuan, Shi Wei and Lawati, Noof Al and Zhi, Maoqing and Yang, Mengya and Müller, Jolanda Simone and Stewart, Katherine and Kim, Ji-Seon and Nelson, Jenny and Eslava, Salvador (2025) Enhanced solar water oxidation and unassisted water splitting using graphite-protected bulk heterojunction organic photoactive layers. NATURE ENERGY, in pre. ISSN 2058-7546

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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.

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