Mechanical-Electrical-Moisture Stable Ultra-Flexible Perovskite and Organic Solar Cells

Flexible/foldable solar cells (SCs) have a lot of market potential for applications in photovoltaics integrated into buildings and wearable electronics because they are lightweight, shockproof, and self-powered. Additionally, solution-processed flexible/foldable perovskite SCs feature low cost, low carbon and low power consumption in production, shortened payback time, simple fabrication, and attractive power conversion efficiency (PCE) &gt;20% (comparable to typical c-Si SCs). However, electrodes of organic/perovskite SCs such as widely adopted indium-tin-oxide (ITO) electrodes are formed by physical deposition methods (e.g., sputtering and thermal evaporation) which are high power consumption, large carbon footprint, and incompatible with high throughput production, thus hindering further development. Moreover, developing efficient flexible/foldable SCs with super-flexibility (foldability) is still challenging due to the poor mechanical durability of typical ITO electrodes.<br/>We recently developed an in-situ solution-processed method (iSPM) to achieve a new class of foldable transparent electrodes (FTEs) composed of metal-oxide nanoparticles (MONPs) and silver nanowires (AgNWs) [1]. Strategically, the iSPM enables the fabricated substrate-integrated FTEs through the unique tri-system integration including (i) AgNW-AgNW, (ii) MONP-MONP, and (iii) AgNW-MONP systems. Based on the new electrode, the foldable perovskite and organic SCs with very good stability against multi-loading (mechanical-electrical-moisture) operation with folding radius as small as 0.75mm, humidity 85% and continuous electrical bias operations have been demonstrated. To further improve device performances, we have introduced several strategies to the perovskite and organic active layers including modulating the mixing Gibbs free energy [2], dielectric constant of the organic materials [3], and reconstructing subsurface lattice for stable perovskite [Joule 8, 1, 2024]. The PCE of the organic and perovskite SCs can reach over 19% [Nature Comm., 15, 2103, 2024] and 25.2% [Joule 8, 1, 2024].<br/><br/>[1] J. Kim, W.C.H. Choy, et al, Nature Commun., 15, 2070, 2024.<br/>[2] X. He, W.C.H. Choy, et al, Adv. Energy Mater., 202203697, 2023.<br/>[3] X. He, W.C.H. Choy, et al, Nature Comm., 15, 2103, 2024.<br/>[4] Z.W. Gao, W.C.H. Choy, et. al, Joule 8, 1, 2024.