Representative structures of the 2D layered nanofillers covered in this review article along with the illustration of the possible interactions occurring in the resulting PCE. The illustration regarding the interactions within a PCE is partially inspired by Oreffo et al.[134]Graphene oxide (GO): Reproduced under the terms of the CC BY 4.0 license.[38]Copyright 2018, The authors, published by Springer Nature. Boron nitride (h-BN): Reproduced with permission.[39]Copyright 2009, American Physical Society. Transition metal dichalcogenides: Reproduced with permission.[40]Copyright 2011, Springer Nature Customer Service Centre GmbH. MXenes: Reproduced with permission.[41]Copyright 2020, American Chemical Society. Phosphorene: Reproduced under the terms of the CC BY 3.0 license.[42]Copyright 2014, IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. 2D silicate clays: Reproduced with permission.[43]Copyright 2018, Springer International Publishing Switzerland. Layered double hydroxides (LDHs): Reproduced with permission.[44]Copyright 2015, American Chemical Society. Metal organic frameworks (2D MOF): Reproduced with permission.[45]Copyright 2021, American Chemical Society. Covalent organic frameworks (2D COFs): Reproduced with permission.[46]Copyright 2019, American Chemical Society.
