Assembling Mesoscale‐Structured Organic Interfaces in Perovskite Photovoltaics

: Mesoscale-structured materials offer broad opportunities in extremely diverse applications owing to their high surface areas, tunable surface energy, and large pore volume. These benefits may improve the performance of materials in terms of carrier density, charge transport, and stability. Although metal oxides-based mesoscale-structured materials, such as TiO2 , predominantly hold the record efficiency in perovskite solar cells, high temperatures (above 400 °C) and limited materials choices still challenge the community. A novel route to fabricate organic-based mesoscale-structured interfaces (OMI) for perovskite solar cells using a low-temperature and green solvent-based process is presented here. The efficient infiltration of organic porous structures based on crystalline nanoparticles allows engineering efficient "n-i-p" and "p-i-n" perovskite solar cells with enhanced thermal stability, good performance, and excellent lateral homogeneity. The results show that this method is universal for multiple organic electronic materials, which opens the door to transform a wide variety of organic-based semiconductors into scalable n- or p-type porous interfaces for diverse advanced applications.