@article{341eb31fcada446f9571d1b31e3ad191,
title = "Perspectives on intrinsic toughening strategies and passivation of perovskite films with organic additives",
abstract = "We report on the inclusion of 5-aminovaleric acid (5-AVA)—a bulky, long-chained organic molecule—as an additive to enhance the mechanical integrity of hybrid perovskite films. We studied a range of organic cation additives and found that 5-AVA was the most effective at improving cohesion energy, a key metric of mechanical reliability. MAPbI3 films reinforced with 5-AVA added in 5% concentration increased cohesion energy 12-fold from 0.53 J/m2 to 6.04 J/m2, an effect which is attributed to increased plasticity and crack deflection around grain boundaries of the additive-containing perovskite. The addition of 5-AVA also improves Voc in perovskite solar cells and carrier lifetimes with a minimal decrease in PCE, attributed to passivation reducing defect and trap densities. A Tauc plot analysis of the bandgap shows that 5-AVA increases the band gap of the perovskite, correlating with reduced film stress compared to MAPbI3. As a result, the usage of 5-AVA improves the intrinsic thermomechanical reliability, but this improvement comes at the penalty of slightly reduced device efficiency due to reduced charge extraction from the presence of the bulky, insulating organic additive.",
keywords = "2D perovskite, 5-Aminovaleric acid, Microstructure, Perovskite solar cells, Reliability, Stability",
author = "Matthew Gutwald and Nicholas Rolston and Printz, {Adam D.} and Oliver Zhao and Hannah Elmaraghi and Yichuan Ding and Jinbao Zhang and Dauskardt, {Reinhold H.}",
note = "Funding Information: While the primary benefit of the addition of 5-AVA is seen in its increase in mechanical reliability and stability in air, a possible additional benefit of increased grain sizes is an enhancement of electronic performance [16]. As grain size increases, surface defects become less important and have a less pronounced effect on device performance. To further improve device performance, passivation of defects at surfaces and grain boundaries is critical. Passivation along boundaries has also been shown to improve perovskite stability in oxygen, a noted source of degradation in MAPbI3 [17]. Increasing grain size has been a focus of several previous studies [18,19], and indeed, the best-performing perovskite films in terms of optoelectronic properties are observed with single crystals in the absence of grain boundaries [20]. The data obtained from the AFM images in Fig. 4 confirmed the existence of larger grains and topographical features on the surface of 5-AVA perovskite compared to that of the MAPbI3 control. The measured Rq of 20.3 nm for the 5-AVA perovskite exceeded that of the smoother control film of 10.5 nm. This increase in surface roughness supported the observation from SEM that perovskite with 5-AVA has larger grain sizes and features than control MAPbI3 films.This work was supported by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under Solar Energy Technologies Office (SETO) Agreement Number DE-EE0008559. Additional support was provided by the National Science Foundation Graduate Research Fellowship awarded to N. Rolston under award no. DGE-1656518 and to O. Zhao under award no. DGE-1656518. Part of this work was performed at the Stanford Nano Shared Facilities (SNSF), supported by the National Science Foundation under award ECCS-1542152. Funding Information: This work was supported by the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under Solar Energy Technologies Office (SETO) Agreement Number DE-EE0008559 . Additional support was provided by the National Science Foundation Graduate Research Fellowship awarded to N. Rolston under award no. DGE-1656518 and to O. Zhao under award no. DGE-1656518 . Part of this work was performed at the Stanford Nano Shared Facilities (SNSF) , supported by the National Science Foundation under award ECCS-1542152 . Publisher Copyright: {\textcopyright} 2020 Elsevier B.V.",
year = "2020",
month = jun,
day = "1",
doi = "10.1016/j.solmat.2020.110433",
language = "English (US)",
volume = "209",
journal = "Solar Cells",
issn = "0927-0248",
publisher = "Elsevier",
}