Semitransparent Design of Planar n-i-p Perovskite Solar Cells using a Cost-Effective, Perovskite-Compatible DMD Structure as the Top Electrode

In recent years, a significant emphasis has been placed on developing multi-functional solar cells that integrate new features such as color and transparency, thereby opening up the possibility of unconventional photovoltaic (PV) applications, including building-integrated PV (BIPV) systems, tandem solar cells, and wearable electronics. In particular, the integration of semitransparent (ST) solar cells into buildings as power-generating windows, facades or other aesthetic architectural elements constitutes one of the most intriguing perspectives [1]. Since silicon-based panels are generally opaque and unaesthetic, there has been a growing research interest in emerging thin-film solar cells that can be made truly semitransparent, display different colors, and be easily adapted to any type and surface of buildings. Among third-generation PVs, perovskite solar cells (PSCs) are particularly attractive for these applications owing to their superior performances. Over the past few years, tremendous efforts have been applied to develop esthetic semitransparent perovskite solar cells (ST-PSCs) by exploring various kinds of transparent electrodes, controlling the morphology, and engineering the bandgap of the perovskite absorber [2]. Here, a novel multilayer dielectric/metal/dielectric (DMD) transparent electrode based on non-precious copper (Cu) and molybdenum suboxide (MoOx) is manufactured via thermal evaporation and successfully incorporated as top anode in semitransparent planar n-i-p PSCs. Continuous and percolative Cu films as thin as 9.5 nm are grown onto the oxide surface by means of a pre-deposited ultra-thin Au seed layer, which also acts as an effective Cu diffusion barrier. The final MoOx/Au-seed/Cu/MoOx DMD structure shows a very good trade-off between optical transparency and electrical conductivity as well as a great thermal and mechanical stability. Whilst silver and gold are typically used in such DMD structures [3], their replacement with copper allows for a substantial cost reduction without sacrificing the device performance and stability. Through this strategy, PCEs as high as 12.5%, along with acceptable transparency levels, are successfully achieved. It is also demonstrated that the performance of the fabricated devices can be further improved by introducing specific interfacial layers as well as by incorporating appropriate solvent additives into the perovskite precursor solution. References [1] C. J. Traverse, R. Pandey, M. C. Barr, R. R. Lunt, Nat. Energy 2017, 2, 849. [2] Q. Xue, R. Xia, C. J. Brabec, H.-L. Yip, Energy Environ. Sci. 2018, 11 (7), 1688. [3] E. Della Gaspera, Y. Peng, Q. Hou, L. Spiccia, U. Bach, J. J. Jasieniak, Y.-B. Cheng, Nano Energy 2015, 13, 249. [4] G. Giuliano, S. Cataldo, M. Scopelliti, F. Principato, D. Chillura Martino, T. Fiore, B. Pignataro, Adv. Mater. Technol. 2019, 4 (5), 1800688.