Chen, MinDong, YifanZhang, YiZheng, XiaopengMcAndrews, Gabriel R.Dai, ZhenghongJiang, QiYou, ShuaiLiu, TuoHarvey, Steven P.Zhu, KaiOliveto, VincentJackson, AlecWitteck, RobertWheeler, Lance M.Padture, Nitin P.Dyson, Paul JMcGehee, Michael D.Nazeeruddin, Mohammad KBeard, Matthew C.Luther, Joseph M.2024-06-052024-06-052024-06-052024-05-0810.1021/acsenergylett.4c00988https://infoscience.epfl.ch/handle/20.500.14299/208391WOS:001225132100001Mechanical residual stresses within multilayer thin-film device stacks become problematic during thermal changes because of differing thermal expansion and contraction of the various layers. Thin-film photovoltaic (PV) devices are a prime example where this is a concern during temperature fluctuations that occur over long deployment lifetimes. Here, we show control of the residual stress within halide perovskite thin-film device stacks by the use of an alkyl-ammonium additive. This additive approach reduces the residual stress and strain to near-zero at room temperature and prevents cracking and delamination during intense and rapid thermal cycling. We demonstrate this concept in both n-i-p (regular) and p-i-n (inverted) unencapsulated perovskite solar cells and minimodules with both types of solar cells retaining over 80% of their initial power conversion efficiency (PCE) after 2500 thermal cycles in the temperature range of -40 to 85°C. The mechanism by which stress engineering mitigates thermal cycling fatigue in these perovskite PVs is discussed.Physical SciencesTechnologytext::journal::journal article::research article