Nonprecious Copper‐Based Transparent Top Electrode via Seed Layer–Assisted Thermal Evaporation for High‐Performance Semitransparent n‐i‐p Perovskite Solar Cells

• Published in: Advanced materials technologies 2019-05, Vol.4 (5), p.n/a
• Main Authors: Giuliano, Giuliana, Cataldo, Sebastiano, Scopelliti, Michelangelo, Principato, Fabio, Chillura Martino, Delia, Fiore, Tiziana, Pignataro, Bruno
• Format: Article
• Language: English
• Subjects: copper; molybdenum oxide; perovskite; seed layer; semitransparent
• ISSN: 2365-709X; 2365-709X
• DOI: 10.1002/admt.201800688

Semitransparent perovskite solar cells (ST‐PSCs) are highly attractive for applications in building‐integrated photovoltaics as well as in multijunction tandem devices. To fabricate high‐performance ST‐PSCs, suitable transparent top electrodes are strongly needed. Dielectric/metal/dielectric (DMD) multilayer structures have been shown to be promising candidates, though generally based on high‐value metals such as gold or silver, the latter causing also stability issues by reacting with perovskite. Here, a novel DMD transparent electrode based on nonprecious, less‐reactive copper is developed via thermal evaporation and used as a top anode in the fabrication of high‐performance semitransparent n‐i‐p perovskite solar cells, the best device yielding a power conversion efficiency as high as 12.5%. The DMD architecture consists of a gold‐seeded Cu thin film sandwiched between two MoO x dielectric layers. It is demonstrated that Cu self‐aggregation and diffusion into MoOx can be substantially limited by introducing an ultrathin (1.5 nm) Au seed layer, and conductive Cu films as thin as 9.5 nm can be achieved. A fine tuning of the perovskite layer thickness is also carried out to further enhance the device transparency up to a maximum average visible transmittance approaching 25%. A novel multilayer transparent electrode based on nonprecious copper and molybdenum suboxide is manufactured by thermal evaporation and successfully integrated as hole‐collecting top contact in semitransparent n‐i‐p perovskite solar cells yielding a maximum efficiency of 12.5%. Conductive Cu films as thin as 9.5 nm are grown onto the oxide surface by means of a predeposited ultrathin Au seed layer.