Lai, HuaguiLuo, JinchengZwirner, YannickOlthof, SelinaWieczorek, AlexanderYe, FangyuanJeangros, QuentinYin, XinxingAkhundova, FatimaMa, TianshuHe, RuiKothandaraman, Radha K.Chin, XinyuGilshtein, EvgeniiaMuller, AndreWang, ChangleiThiesbrummel, JarlaSiol, SebastianPrieto, Jose MarquezUnold, ThomasStolterfoht, MartinChen, CongTiwari, Ayodhya N.Zhao, DeweiFu, Fan2022-10-242022-10-242022-10-242022-09-3010.1002/aenm.202202438https://infoscience.epfl.ch/handle/20.500.14299/191635WOS:000862070400001Among various types of perovskite-based tandem solar cells (TSCs), all-perovskite TSCs are of particular attractiveness for building- and vehicle-integrated photovoltaics, or space energy areas as they can be fabricated on flexible and lightweight substrates with a very high power-to-weight ratio. However, the efficiency of flexible all-perovskite tandems is lagging far behind their rigid counterparts primarily due to the challenges in developing efficient wide-bandgap (WBG) perovskite solar cells on the flexible substrates as well as their low open-circuit voltage (V-OC). Here, it is reported that the use of self-assembled monolayers as hole-selective contact effectively suppresses the interfacial recombination and allows the subsequent uniform growth of a 1.77 eV WBG perovskite with superior optoelectronic quality. In addition, a postdeposition treatment with 2-thiopheneethylammonium chloride is employed to further suppress the bulk and interfacial recombination, boosting the V-OC of the WBG top cell to 1.29 V. Based on this, the first proof-of-concept four-terminal all-perovskite flexible TSC with a power conversion efficiency of 22.6% is presented. When integrating into two-terminal flexible tandems, 23.8% flexible all-perovskite TSCs with a superior V-OC of 2.1 V is achieved, which is on par with the V-OC reported on the 28% all-perovskite tandems grown on the rigid substrate.Chemistry, PhysicalEnergy & FuelsMaterials Science, MultidisciplinaryPhysics, AppliedPhysics, Condensed MatterChemistryEnergy & FuelsMaterials SciencePhysicsall-perovskite tandemsflexible tandem solar cellsperovskitev(oc)-deficitwide-bandgapopen-circuit voltagemonolayersefficiencyau(111)solventtext::journal::journal article::research article