Polycrystalline perovskite solar cells show high power conversion efficiencies despite the presence of grain boundaries (GBs). The benign nature of GBs on the electronic properties and structural stability in metal–halide...

A highly efficient multifunctional polyvinylidene fluoride// carbon-molybdenum disulfide (PVDF//C-MoS 2) interlayer is developed by direct deposition on sulfur cathode through facile slide coating method for LiÀ S batteries. The as-developed PVDF//C-MoS 2 interlayer exhibits the polysulfide adsorption and trapping capabilities, which reduces the shuttling effects and also slows down the self-discharge in LiÀ S batteries. The first composite layer (C-MoS 2) on the cathode maximizes the level of lithium polysulfide adsorption owing to the strong dipolar interaction of MoÀ S on the polarized surface of polysulfide species. Moreover, the PVDF layer physically traps/ capture the remaining polysulfide species with its interconnected microstructure for the reutilization as active material in the cathode. The LiÀ S batteries based on interlayers deliver the discharge capacity of 1086 mAh g À 1 at 1 C with 3.0 mg cm À 2 sulfur loading and show capacity decay of 0.04 % per cycle after 1500 cycles. In contrast, the LiÀ S batteries without interlayer merely maintain the discharge capacities of 423 mAh g À 1 at 1 C with 3.0 mg cm À 2 sulfur loading and show severe capacity decay (0.12 %) after 505 cycles. The LiÀ S batteries also depict the remarkable cyclic performances with as-developed interlayer for high sulfur loading cathodes and efficiently slowdowns the self-discharge even after resting for a long time.

Dilute donor organic solar cells (OSCs) aim to circumvent the trade-off between open-circuit voltage V oc and short-circuit current density j sc by decreasing the donor/acceptor interface. The main challenge of such an architecture is to realize hole extraction pathways. Due to the reduced donor content, there are negligible percolation paths toward the contacts for the photogenerated holes. Hole transport toward the contacts can either happen by tunneling between the diluted polymers, hole backtransfer to the acceptor, and rarely percolation to the contacts along polymers. However, the detailed morphology of the polymer network strongly controls which is the dominant mechanism and its impact on solar cell performance. We present a kinetic Monte Carlo (kMC) study on the role of the morphology on the performance of diluted donor OSCs with a donor fraction of ∼1 wt %. The photocurrent generation is investigated for different offsets between the acceptor and donor highest occupied molecular orbitals (HOMO) and different morphologies. Due to the low donor concentration used, we only consider hole back-transfer and percolation along polymer networks. We analyze three different morphologies: isolated polymer chains (SAW), polymer chain networks touching the contacts (NTC), and polymer networks not touching the contact (NNTC). Our results show that even a minor amount of polymers forming percolation paths to the contact is sufficient to generate a substantial photocurrent and keep a high V oc . Polymer chains with longer chain length provide substantial short-circuit current from the hole back-transfer to the acceptor even at high HOMO offsets of 0.6 eV.