• Energy Research

The present work applies a focal point of materials-related issues to review the major case studies of electron transport layers (ETLs) of metal halide perovskite solar cells (PSCs) that contain graphene-based materials (GBMs), including graphene (GR), graphene oxide (GO), reduced graphene oxide (RGO), and graphene quantum dots (GQDs). The coverage includes the principal components of ETLs, which are compact and mesoporous TiO2, SnO2, ZnO and the fullerene derivative PCBM. Basic considerations of solar cell design are provided and the effects of the different ETL materials on the power conversion efficiency (PCE) have been surveyed. The strategy of adding GBMs is based on a range of phenomenological outcomes, including enhanced electron transport, enhanced current density-voltage (J-V) characteristics and parameters, potential for band gap (Eg) tuning, and enhanced device stability (chemical and environmental). These characteristics are made complicated by the variable effects of GBM size, amount, morphology, and distribution on the nanostructure, the resultant performance, and the associated effects on the potential for charge recombination. A further complication is the uncertain nature of the interfaces between the ETL and perovskite as well as between phases within the ETL.

Anode‐free lithium metal batteries (AFLMBs) show promise as a means of further enhancing the energy density of current lithium‐ion batteries, as they do not require conventional graphite anodes. The anode‐free configuration, however, suffers from inferior chemical stability of the solid electrolyte interphase (SEI) layer and experiences inhomogeneous lithium deposition during charge/discharge processes, resulting in rapid capacity fading. To address these issues, a carbonized polydopamine (CPD) coating is applied to the copper current collector. The CPD‐coated copper current collector promotes highly efficient and reversible lithium plating and stripping processes, resulting in a densely packed lithium deposition that significantly improves cycling stability. The anode‐free full cell, consisting of CPD‐coated copper current collector and a LiFePO4 cathode, demonstrates significantly improved electrochemical performance, with a capacity retention of more than 63% after 100 cycles at a current rate of 0.3C. The stability of the SEI layer and the presence of lithiophilic sites are verified through a range of techniques, including optical microscopy, Raman spectroscopy, X‐ray photoelectron spectroscopy, chronoamperometry, and electrochemical impedance spectroscopy. Based on these collective findings, it can be inferred that the use of CPD coating provides a simple way to enhance the electrochemical performance of AFLMBs.