RESUMO
Layered two-dimensional (2D) materials have gained popularity thanks to their atomically thin physique and strong coupling with light. Here, we investigated a wide band gap (≥ 2 eV) 2D material, i.e., tin disulfide (SnS2), and decorated it with silver nanoparticles, Ag-NPs, for broadband photodetection. Our results show that the SnS2/Ag-NPs devices exhibit broadband photodetection ranging from the ultraviolet to near-infrared (250-1050 nm) spectrum with decreased rise/decay times from 8/20 s to 7/16 s under 250 nm wavelength light compared to the bare SnS2 device. This is attributed to the localized surface plasmon resonance effect and the wide band gap of SnS2 crystal. Furthermore, the HfO2-passivated SnS2/Ag-NPs devices exhibited high photodetection performance in terms of photoresponsivity (â¼12 500 A W-1), and external quantum efficiency (â¼6 × 106%), which are significantly higher compared to those of bare SnS2. Importantly, after HfO2 passivation, the SnS2/Ag-NPs photodetector maintained the stable performance for several weeks with merely â¼5.7% reduction in photoresponsivity. Lastly, we fabricated a flexible SnS2/Ag-NPs photodetector, which shows excellent and stable performance under various bending curvatures (0, 20, and 10 mm), as it retains â¼80% of its photoresponsivity up to 500 bending cycles. Thus, our study provides a simple route to realize broadband and stable photoactivity in flexible 2D material-based devices.
RESUMO
Excellent power conversion efficiency (PCE) and stability are the primary forces that propel the all-inorganic cesium-based halide perovskite solar cells (PSCs) toward commercialization. However, the intrinsic high density of trap state and internal nonradiative recombination of CsPbIBr2 perovskite film are the barriers that limit its development. In the present study, a facile additive strategy is introduced to fabricate highly efficient CsPbIBr2 PSCs by incorporating sulfamic acid sodium salt (SAS) into the perovskite layer. The additive can control the crystallization behaviors and optimize morphology, as well as effectively passivate defects in the bulk perovskite film, thereby resulting in a high-quality perovskite. In addition, SAS in perovskite has possibly introduced an additional internal electric field effect that favors electron transport and injection due to inhomogeneous ion distribution. A champion PCE of 10.57% (steady-output efficiency is 9.99%) is achieved under 1 Sun illumination, which surpasses that of the contrast sample by 16.84%. The modified perovskite film also exhibits improved moisture stability. The unencapsulated device maintains over 80% initial PCE after aging for 198 h in air. The results provide a suitable additive for inorganic perovskite and introduce a new conjecture to explain the function of additives in PSCs more rationally.
RESUMO
Metal halide perovskite solar cells (PVSCs) have revolutionized photovoltaics since the first prototype in 2009, and up to now the highest efficiency has soared to 24.2%, which is on par with commercial thin film cells and not far from monocrystalline silicon solar cells. Optimizing device performance and improving stability have always been the research highlight of PVSCs. Metal cations are introduced into perovskites to further optimize the quality, and this strategy is showing a vigorous development trend. Here, the progress of research into metal cations for PVSCs is discussed by focusing on the position of the cations in perovskites, the modulation of the film quality, and the influence on the photovoltaic performance. Metal cations are considered in the order of alkali cations, alkaline earth cations, then metal cations in the ds and d regions, and ultimately trivalent cations (p- and f-block metal cations) according to the periodic table of elements. Finally, this work is summarized and some relevant issues are discussed.
