Filters

20233

More filters

20243
Reset filters

Settings

DDC: 530 × DDC: 540 × Type: article × Subject: Lead compounds ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Towards low-temperature processing of efficient γ-CsPbI3 perovskite solar cells
    (London [u.a.] : RSC, 2023) Zhang, Zongbao; Ji, Ran; Hofstetter, Yvonne J.; Deconinck, Marielle; Brunner, Julius; Li, Yanxiu; An, Qingzhi; Vaynzof, Yana
    Inorganic cesium lead iodide (CsPbI3) perovskite solar cells (PSCs) have attracted enormous attention due to their excellent thermal stability and optical bandgap (∼1.73 eV), well-suited for tandem device applications. However, achieving high-performance photovoltaic devices processed at low temperatures is still challenging. Here we reported a new method for the fabrication of high-efficiency and stable γ-CsPbI3 PSCs at lower temperatures than was previously possible by introducing the long-chain organic cation salt ethane-1,2-diammonium iodide (EDAI2) and regulating the content of lead acetate (Pb(OAc)2) in the perovskite precursor solution. We find that EDAI2 acts as an intermediate that can promote the formation of γ-CsPbI3, while excess Pb(OAc)2 can further stabilize the γ-phase of CsPbI3 perovskite. Consequently, improved crystallinity and morphology and reduced carrier recombination are observed in the CsPbI3 films fabricated by the new method. By optimizing the hole transport layer of CsPbI3 inverted architecture solar cells, we demonstrate efficiencies of up to 16.6%, surpassing previous reports examining γ-CsPbI3 in inverted PSCs. Notably, the encapsulated solar cells maintain 97% of their initial efficiency at room temperature and under dim light for 25 days, demonstrating the synergistic effect of EDAI2 and Pb(OAc)2 in stabilizing γ-CsPbI3 PSCs.
  • Thumbnail Image
    Item
    Influence of chemical interactions on the electronic properties of BiOI/organic semiconductor heterojunctions for application in solution-processed electronics
    (London [u.a.] : RSC, 2023) Lapalikar, Vaidehi; Dacha, Preetam; Hambsch, Mike; Hofstetter, Yvonne J.; Vaynzof, Yana; Mannsfeld, Stefan C. B.; Ruck, Michael
    Bismuth oxide iodide (BiOI) has been viewed as a suitable environmentally-friendly alternative to lead-halide perovskites for low-cost (opto-)electronic applications such as photodetectors, phototransistors and sensors. To enable its incorporation in these devices in a convenient, scalable, and economical way, BiOI thin films were investigated as part of heterojunctions with various p-type organic semiconductors (OSCs) and tested in a field-effect transistor (FET) configuration. The hybrid heterojunctions, which combine the respective functionalities of BiOI and the OSCs were processed from solution under ambient atmosphere. The characteristics of each of these hybrid systems were correlated with the physical and chemical properties of the respective materials using a concept based on heteropolar chemical interactions at the interface. Systems suitable for application in lateral transport devices were identified and it was demonstrated how materials in the hybrids interact to provide improved and synergistic properties. These indentified heterojunction FETs are a first instance of successful incorporation of solution-processed BiOI thin films in a three-terminal device. They show a significant threshold voltage shift and retained carrier mobility compared to pristine OSC devices and open up possibilities for future optoelectronic applications.
  • Thumbnail Image
    Item
    Remarkable performance recovery in highly defective perovskite solar cells by photo-oxidation
    (London [u.a.] : RSC, 2023) Goetz, Katelyn P.; Thome, Fabian T. F.; An, Qingzhi; Hofstetter, Yvonne J.; Schramm, Tim; Yangui, Aymen; Kiligaridis, Alexander; Loeffler, Markus; Taylor, Alexander D.; Scheblykin, Ivan G.; Vaynzof, Yana
    Exposure to environmental factors is generally expected to cause degradation in perovskite films and solar cells. Herein, we show that films with certain defect profiles can display the opposite effect, healing upon exposure to oxygen under illumination. We tune the iodine content of methylammonium lead triiodide perovskite from understoichiometric to overstoichiometric and expose them to oxygen and light prior to the addition of the top layers of the device, thereby examining the defect dependence of their photooxidative response in the absence of storage-related chemical processes. The contrast between the photovoltaic properties of the cells with different defects is stark. Understoichiometric samples indeed degrade, demonstrating performance at 33% of their untreated counterparts, while stoichiometric samples maintain their performance levels. Surprisingly, overstoichiometric samples, which show low current density and strong reverse hysteresis when untreated, heal to maximum performance levels (the same as untreated, stoichiometric samples) upon the photooxidative treatment. A similar, albeit smaller-scale, effect is observed for triple cation and methylammonium-free compositions, demonstrating the general application of this treatment to state-of-the-art compositions. We examine the reasons behind this response by a suite of characterization techniques, finding that the performance changes coincide with microstructural decay at the crystal surface, reorientation of the bulk crystal structure for the understoichiometric cells, and a decrease in the iodine-to-lead ratio of all films. These results indicate that defect engineering is a powerful tool to manipulate the stability of perovskite solar cells.