Charge transport, extraction, and collection play important roles in the working process of organic solar cells (OSCs), and the interface engineering is one of the key factors to realize the high-throughput printing fabrication of OSCs. The structure design or doping of electrode interlayer materials can effectively suppress the recombination of carriers at the interface and improve the ohmic contact between the active layer and the electrodes, which is a useful method to achieve a high power conversion efficiency (PCE). Poly­(9,9-bis­(3′-(N,N-dimethyl)-N-ethylammoniumpropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene))­dibromide (PFN-Br) is a widely used alcohol-soluble cathode interlayer material. By doping PFN-Br with melamine (MA), the charge extraction efficiency and nongeminate recombination at the cathode interface are successfully optimized. Finally, the device efficiencies of PM6:Y6 and PM6:BTP-eC9 are increased to an amazing 17.44% and 18.58%, respectively. This work provides a new strategy for the fabrication of high-efficiency OSCs.

An interface modification layer plays an important role in improving the performance of organic solar cells (OSCs). The structure design or doping of electrode interlayer materials can effectively inhibit interfacial carrier recombination and improve ohmic contact between the active layer and the electrodes, which is desirable for r e a l i z i n g h i g h p o w e r c o n v e r s i o n e ffi c i e n c i e s ( P C E s ) . P o l y ( 3 , 4ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been extensively used as a hole-transport layer (HTL) in OSCs. Here, a modification of PEDOT:PSS is proposed using sulfonated graphene (SG) as a secondary dopant for improving the surface morphology and conductivity. The incorporation of the SG-doped PEDOT:PSS as the HTLs in OSCs leads to the increased charge extraction and shows the best PCEs of 17.48% for PM6:Y6 devices and 18.56% for PM6:L8-BO devices. The significant improvement in device performance suggests that SG-PEDOT:PSS is a promising interfacial layer for efficient charge transport and extraction toward high-efficiency OSCs.

In all-polymer solar cells (all-PSCs), there remains such a dilemma that obtains good miscibility and crystallinity simultaneously. Herein a new family of Y-shape polymer acceptor, namely PYTT is developed, which is copolymerized from Y6 and benzotrithiophene units in three-way directions. Benefiting from its high-density end-chains and extended 𝝅-conjugation thanks to highly-branched 3D architecture, PYTT displays better organic solubility despite much higher molecular weights, larger crystallinity, and tighter 𝝅-stacking than the linear counterpart-PYT comprising Y6 and thiophene moieties, while showing identical optical absorption yet threefold higher photoluminescence intensity. In PYTT blend film with PM6 polymer donor, the interpenetrating nano-fibrillar structures are formed with well-intermixed polymeric domain sizes close to the exciton diffusion length, which is greatly conducive to exciton dissociation and charge transport in device. Consequently, PYTT-based all-PSCs exhibit all increased photovoltaic parameters, yielding a decent power conversion efficiency of 15.60%, which is ≈20% enhancement over PYT-based device, along with low nonradiative loss of 0.221 meV.

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Fe, N-doped carbon spheres as high-efficiency ORR catalysts were prepared by a facile electrospinning process.