1. Shenzhen Research Institute of Shandong University, Shenzhen 518000, China
2. School of Integrated Circuits, Shandong University, Jinan 710016, China
3. College of Nuclear Science and Technology, Naval University of Engineering, Wuhan 430033, China
Inverted (p-i-n) perovskite solar cells have attracted significant attention due to their excellent stability potential and process compatibility. Among the key materials, [6,6]phenyl-C61-butyric acid methyl ester (PCBM) plays an irreplaceable role as the electron transport layer material. However, the conventional PCBM layer is often regarded as a simple electron extraction and physical capping layer. Its inherent light/heatinduced dimerization and nonideal contact with perovskite surface defects severely limit further improvements in device efficiency and longterm stability. This review summarizes the recent paradigm shift in the field of PCBM-perovskite interface engineering, from simple coverage to active regulation. First, the root causes of instability and device performance degradation associated with PCBM in perovskite solar cells are analyzed. Then, three cutting-edge strategies for actively regulating the modified PCBM electron transport layer are focused. The first strategy uses molecular dopants to guide the ordered arrangement of PCBM molecules, optimize energy levels and inhibit dimerization. The second strategy involves designing and synthesizing functionalized PCBM derivatives,which endow the interface layer with the ability to chemically capture iodine molecules, and promote their dissociation and regeneration into iodide ions for dynamic selfhealing. The third strategy employs in-situ polymerization to construct a three-dimensional network structure, which physically suppresses the thermal aggregation and phase separation of PCBM molecules while enhancing interfacial mechanical coupling through coordination bonds. Research results show that these active interface engineering strategies achieve simultaneous breakthroughs in device efficiency (over 26%) and operational stability (eg, over 1000 h under maximum power point tracking) by synergistically optimizing molecular arrangement, energy level alignment, defect passivation and iodine cycle management. Finally, this review provides design insights for developing PCBM electron transport layers that are both commercially viable and multifunctional, offering a pathway to efficient and stable perovskite photovoltaic devices.