Organic Polymer Semiconductor Photocatalysts: From Building Block Design to Controllable Assembly

Abstract Organic polymer semiconductors are emerging as a promising class of photocatalysts because their highly tunable molecular structures and flexible morphological control offer unique advantages for overcoming the efficiency bottlenecks of traditional inorganic materials. However, the development of organic polymer photocatalysts largely relies on empirical, trial‐and‐error approaches. The understanding of their structure–activity relationship is insufficient, which significantly hinders the rational design and performance prediction of polymer photocatalysts. This review systematically outlines the structure‐driven design strategies for polymer photocatalysts by focusing on two interconnected levels: molecular building block design and controllable assembly. Starting with the molecular building block design, strategies including monomer unit selection, functional group modification, and heteroatom doping are analyzed in detail for tuning the material's intrinsic electronic and photophysical properties. At the assembly level, we explore how strategies like morphological control, surface modification, and pore engineering can guide the controlled organization of polymers to optimize the final semiconductor architecture. By establishing the relationship between structure and properties at different scales, we aim to build a systematic structure–activity relationship for polymer photocatalysts, ultimately seeking to shift from empirical screening to rational design.