Organic semiconductors are increasingly recognised as promising materials for solar fuels photocatalysis due to their structural tunability, visible light absorption, and potential for low-energy synthesis. This talk will discuss recent advances in constructing organic donor–acceptor heterojunctions using micro and meso-porous materials. A particular focus will be on strategies to achieve efficient charge separation and transport through heterojunction formation, which can overcome intrinsic recombination losses common in single-component systems.

Conventional methods to form heterojunctions—such as nanoprecipitation or nanoemulsion—are typically restricted to organic semiconductors that are soluble in organic solvents. As a result, these methods are best suited to linear, “OPV-type” polymers that are non-porous. This limitation excludes many of the most promising photocatalysts, including insoluble 2D conjugated polymers and network materials that exhibit long-range order and porosity that can allow for efficient interaction of redox active reagents and active sites. In particular, hydrophilic microporosity—engineered via backbone design or post-polymerisation modification—plays a vital role in improving wettability and electrolyte accessibility, thus enhancing photocatalytic performance. The degree to which water integrates into organic semiconductor materials also significantly changes the kinetics of charge generation and lifetime.

We explore templated growth approaches that enable the controlled assembly of chemically distinct but topologically matched donor and acceptor polymers into coherent heterojunctions. This strategy allows for the integration of insoluble and rigid materials into defined interfacial architectures that promote ultrafast charge separation and suppress recombination. Templated donor–acceptor heterostructures show significantly enhanced hydrogen evolution activity compared to their individual components and are capable of generating long-lived charges under non-sacrificial conditions. The strategy provides a modular pathway to build efficient organic heterojunctions using materials traditionally excluded from conventional processing.

By bridging synthetic design, supramolecular assembly, and interface engineering, this approach opens up a new class of materials for heterojunction formation and present new possibilities for cocatalyst integration in light-driven hydrogen evolution and carbon dioxide reduction by organic semiconductors.