Magnetic\nNanocomposite Modified Hybrid Hole-Transport\nLayer for Constructing Organic Solar Cells with High Efficiencies

An\ninterface modification layer holds paramount significance in\nreducing interface carrier recombination and improving the ohmic contact\nbetween the active layer and the electrode in organic solar cells\n(OSCs). Modifying or doping the widely used hole-transport layer (HTL)\nPEDOT:PSS to adjust the work function, conductivity, and acidity has\nbecome a common strategy for achieving high-performance OSCs. Metal\noxides and two-dimensional materials as secondary dopants into PEDOT:PSS,\nrespectively, as well as a replacement of PEDOT:PSS both exhibit immense\npotential for achieving high-performance OSCs due to their excellent\nelectrical properties. Herein, we report a method utilizing a Fe<sub>3</sub>O<sub>4</sub>/GO magnetic nanocomposite as a secondary dopant\nfor PEDOT:PSS to modulate its inherent properties for constructing\nhigh-efficiency OSCs. The magnetic nanocomposite hybrid HTL exhibits\na suitable optical transmittance and higher work function. Meanwhile,\nit is found that the addition of Fe<sub>3</sub>O<sub>4</sub>/GO magnetic\nnanoparticles expands the domain of PEDOT and enhances the phase separation\nbetween PEDOT and PSS segments, thereby improving the conductivity\nof PEDOT:PSS. By fine-tuning the doping ratio of a Fe<sub>3</sub>O<sub>4</sub>/GO magnetic nanocomposite in PEDOT:PSS, the best power conversion\nefficiency of OSCs based on PM6:L8-BO was up to 18.91%. The notable\nenhancement of the device’s performance was due to the enhanced\nhole mobility and the improved charge extraction, further complemented\nby the decreased likelihood of interface recombination brought about\nby the hybrid HTL. Compared with PEDOT:PSS-based OSCs, an enhanced\nstability of the hybrid HTL-based device was also obtained. In addition,\nthe diverse adaptability of the hybrid HTL was demonstrated in enhancing\nthe performance of OSCs that are based on PM6:Y6 and PBDB-T:ITIC.\nThe effectiveness and versatility of a magnetic nanocomposite hybrid\nHTL present opportunities for achieving high-performance OSCs.