Perovskite is an emerging material for high performance solar cell application with low-cost solution-processable fabrication. As an ink, perovskite composition can be easily modified to create semi-transparent solar cells for window replacement. To enable scalable large-scale production, the spray process is one of the major candidates. In this work, we developed sequential spray deposition (SSD) to create double layer absorbers from different dimensional perovskites. SSD, for the first time, achieves layer-by-layer deposition of different perovskite materials for stacked architecture. To demonstrate the benefits, we spray-coated lower dimension, more stable perovskite onto high performance yet sensitive 3D semi-transparent perovskite. SSD performed under a humid environment (40 - 50% RH) brings about better film stability and retains good performance of 3D perovskite. Sequential spray deposition opens new routes for various stacking designs and large-scale production under economical ambient conditions.
Perovskite materials are emerging as suitable materials for low-cost, high efficiency optoelectronics. In this study, we reported the surface modification of 2D (PEA)2PbBr4 for violet emission using PEG doping followed by a newly developed step called swift cation doping (SCD) where phenylethylammonium cations (PEA+) in isopropanol (IPA) are abruptly applied during crystallization. 2D Perovskite doped with PEG using SCD resulted in smaller grain, smoother surface, higher film density, higher photoluminescence quantum efficiency, and longer average PL lifetime. These features are highly beneficial for photoluminescence application and can be easily applied to enhance other perovskite LED thin films.
Rapid advancements in perovskite materials have led to potential applications in various optoelectronic devices, such as solar cells, light-emitting diodes, and photodetectors. Due to good photoelectric properties, perovskite enables low-cost and comparable performance in terms of responsivity, detectivity, and speed to those of the silicon counterpart. In this work, we utilized triple cation perovskite, well known for its high performance, stability, and wide absorption range, which is crucial for broadband photodetector applications. To achieve improved detectivity and faster response time, graded multilayer perovskite absorbers were our focus. Sequential spray deposition, which allows stacked perovskite architecture without disturbing lower perovskite layers, was used to generate single, double, and triple-layer perovskite photodetectors with proper energy band alignment. In this work, we achieved a record on self-powered perovskite photodetector fabricated from a scalable spray process in terms of EQE and responsivity of 65.30% and 0.30 A W-1. The multilayer devices showed faster response speed than those of single-layer perovskite photodetectors with the champion device reaching 70 µs and 88 µs for rising and falling times. The graded band structure and the internal electric field generated from perovskite heterojunction also increase specific detectivity about one magnitude higher in comparison to the single-layer with the champion device achieving 6.82 × 1012 cmHz1/2 W−1.
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