Batteries for high-rate applications such as electric vehicles need to be efficient at mobilizing charges (both electrons and ions). To this end, choice of the conductive carbon in the electrode can make a significant difference in the performance of the electrode. In this work, graphene nanoribbons (GNRs) are explored as conductive pathways for a silicon-based anode. Water-based electrospinning is employed to directly deposit poly(vinyl alcohol) (PVA)−silicon−graphene nanoribbon composite fibers on a copper current collector. The size of the employed GNRs dictates their placement: either inside each fiber (small GNRs) or as a bridge between multiple fibers (large GNRs). Galvanostatic charge/discharge cycles reveal that fibers with GNRs have higher capacity and overall retention compared to those with corresponding precursor carbon nanotubes (CNTs). To further distinguish the effectiveness of GNRs as the conductive agent, samples with two GNRs and their parent CNTs were subject to rate-capability tests. Fibers with large GNR inclusions exhibit an excellent performance at fast rates (1400 mAh g −1 at 12.6 A g −1 ). For both pairs, enhancement in the performance of GNRs over CNTs grows with increasing rates. Finally, a small amount of large GNRs (1 wt %) is blended with small GNRs in the fibers to create synergy between intra-and interconductivity provided by small and large GNRs, respectively. The resulting fiber mat exhibits the same capacity as that of only small GNRs, even at a current rate that is 4 times higher (300 mAh g −1 at 21 A g −1 ).

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Metal halide perovskites are versatile materials which have already demonstrated exceptional performance in diverse optoelectronic devices. The progress has been significant; however, the fundamental understanding of the physics of charge injection remains elusive, impeding further advancements. Here, we use field-effect transistors (FETs) to investigate the impact of surface functionalization on the charge injection and transport in thin films of phenethylammonium tin iodide (PEA2SnI4). We show that self-assembled monolayers (SAMs) can both assist in reducing the Schottky barrier and act as an ion blocking layer between the contact and the perovskite film, limiting interfacial chemical reactions. Consequently, the contact resistance is lowered by more than 3 times compared to untreated contacts. The temperature dependence of the charge carrier mobility is discussed considering the contributions from the channel and contacts, respectively. Our results provide a quantitative framework for the charge injection in metal halide perovskites and will contribute toward the progress of high-performance optoelectronic devices including solar cells, light-emitting diodes, as well as X-ray and photodetectors.