Carbon-based perovskite solar cells (C-PSCs) are widely accepted as stable, cost-effective photovoltaics. However, C-PSCs have been suffering from relatively low power conversion efficiencies (PCEs) due to severe electrode-related energy loss. Herein, we report the application of a single-atom material (SAM) as the back electrode in C-PSCs. Our Ti1/rGO consists of single titanium (Ti) adatoms anchored on reduced graphene oxide (rGO) in a welldefined Ti1O4-OH configuration capable of well tuning the electronic properties of rGO. The downshift of the Fermi level notably minimizes the series resistance of the carbon-based electrode. By combining with an advanced modular cell architecture, a steady-state PCE of up 2 to 20.6% for C-PSCs is finally achieved. Furthermore, the device without encapsulation tracked at the maximum power point under one-sun illumination retains 90% of its initial value after 1000 h.the devices without encapsulation retain 98% and 95% of their initial values for 1300 h under 1-sun illumination at 25 o C and 60 o C, respectively.

Carbon-based single-atom catalysts (C-SACs), featured with flexible, well-defined atomic geometry and superior electrical conductivity, have experienced a rapid development in the last decade and proved unique opportunities in selective oxygen...

Atomic transition‐metal‐nitrogen‐carbon catalysts (M‐N‐Cs) hold great promise as Pt‐group‐metal‐free candidates for electrochemical reactions, yet their rational design and controllable synthesis remain fundamental challenges. Here, the molten‐salts mediated pyrolysis is demonstrated to be an effective and facile strategy for simultaneous morphology and electronic structure modulation of prototypical Fe‐N‐C materials, which functions as efficient oxygen reduction electrocatalysts. Taking advantage of the strong polarity and salt templating effects, the as‐obtained Fe‐N/C‐single atom catalyst (SAC) possesses hierarchical porous nanosheet morphology with an impressive specific surface area of 2237 m2 g−1 and unique FeN4Cl moieties as isolated active centers. The Fe‐N/C‐SAC delivers remarkable alkaline oxygen reduction reaction (ORR) activity with a half‐wave potential of 0.91 V and record kinetic current density up to 55 mA cm−2, outperforming the benchmark Pt/C. By virtue of dechlorination treatment, it is experimentally identified that the enhanced ORR activities are essentially governed by the axially bound Cl. Theoretical calculations rationalize this finding and demonstrate that the well‐defined fivefold‐coordinated configuration accelerates 4e− pathway kinetics through near‐optimal adsorption of the *OH intermediates and tunes the potential determining step from *OH reduction to *OOH formation. This study provides fundamental insights into the coordination‐engineered strategy in single‐atom catalysis.