Introducing Organic Interlayer over Self Assembled Monolayers: Boosting Stability of Solution Processable P-I-N based Perovskite Solar Cells with nearly 20% efficiency

Perovskite solar cells (PSCs) have been deeply studied for its growing photovoltaic performance in various ways. Such achievement are due to fine optimization of the stacking layers and experimenting in suitable device architecture. Use of interlayers has been in positive effect in the fabrication process in improving the efficiency and other parameters. In the past couple of years, self-assembled monolayers (SAM) have been subjected for use as an alternative or a replacement as Hole Transport Layer (HTL)1. SAM has been in the limelight due to its efficient passivating nature at the hole selective interface and a faster charge extraction2. Stability of PSCs is fundamental to get reliable results that can be transferred to market potential, during the last years standard stability procedure have been validated also for PSCs, suggesting that research community must conduct stability tests to confirm the benefit of any kind of modification 3, 4. Here, for the first time, we have introduced an interlayer small organic molecule 2- decyl[1]benzothieno[3,2-b][1]benzothiophene (C10-BTBT ) over HTL self-assembled monolayer (2-(3,6-Dimethoxy-9H-carbazol-9-yl) ethyl) phosphonic acid also known as Meo-2PACz. This new usage of interlayer over SAM has shown a boost in efficiency giving a maximum power conversion efficiency of 19.6%, with remarkable stability over light soaking test (ISOS L-1), showing a T80 of 712h by using solution processable electron transport layers, such as Phenyl-C61- butyric acid methyl ester (PCBM) and Bathocuproine (BCP), further proving the suitability of this approach over industrial upscalable R2R technique. This approach can be extended as a common procedure to reduce the non-radiative loss at the interface between hole selective contact SAM and perovskite layer. [1] Magomedov, Artiom, Amran Al-Ashouri, Ernestas Kasparavi?ius, Simona Strazdaite, Gediminas Niaura, Marko Jo?t, Tadas Malinauskas, Steve Albrecht, and Vytautas Getautis. "Self-assembled hole transporting monolayer for highly efficient perovskite solar cells." Advanced energy materials 8, no. 32 (2018): 1801892. [2] Choi, Kyoungwon, Hyuntae Choi, Jihyun Min, Taewan Kim, Dohyun Kim, Sung Yun Son, Guan-Woo Kim, Jongmin Choi, and Taiho Park. "A Short Review on Interface Engineering of Perovskite Solar Cells: A Self-Assembled Monolayer and Its Roles." Solar RRL 4, no. 2 (2020): 1900251. [3] Khenkin, Mark V., Eugene A. Katz, Antonio Abate, Giorgio Bardizza, Joseph J. Berry, Christoph Brabec, Francesca Brunetti et al. "Consensus statement for stability assessment and reporting for perovskite photovoltaics based on ISOS procedures." Nature Energy 5, no. 1 (2020): 35-49. [4] Castriotta, Luigi Angelo, Rosinda Fuentes Pineda, Vivek Babu, Pierpaolo Spinelli, Babak Taheri, Fabio Matteocci, Francesca Brunetti, Konrad Wojciechowski, and Aldo Di Carlo. "Light-Stable Methylammonium-Free Inverted Flexible Perovskite Solar Modules on PET Exceeding 10.5% on a 15.7 cm2 Active Area." ACS Applied Materials & Interfaces 13, no. 25 (2021): 29576-29584.