Multieffect coupled NGs with sandwich layer configuration. (a) Pyro-photovoltaic NG on the basis of sandwich-structured ITO/BTO/Ag [43
]. Copyright 2018, Elsevier. (b) Piezo-pyro-photovoltaic NG with ITO/BTO/Ag sandwich configuration [15
]. Copyright 2019, Royal Society of Chemistry. (c) Thermo-photovoltaic NG on the basis of ITO/Br:SnSe/Ag sandwich architecture [17
]. Copyright 2019, Elsevier. (d) Thermo-photovoltaic NG based on sandwich-structured ITO/ZnO/Ag [40
]. Copyright 2019, Wiley.