A Wide Bandgap Halide Perovskite Based Self‐Powered Blue Photodetector with 84.9% of External Quantum Efficiency

Abstract

design of vertically stacked diode-type photodetectors (PDs) resembling the Foveon structure. [1,2] The Foveon PDs based on Si diodes were introduced in late 1999 as an alternative to the most widely used Bayer-type PDs. [3] The former consists of vertically stacked three individual detectors, which selectively absorb incident blue/green/red light along the depth of light penetration in a single pixel. In contrast, the latter consists of laterally arrayed detectors underneath dissipative color filters of blue/green/green/red where a single pixel includes a package of lateral four color filters. [4] Therefore, a vertically staked PD reduces photon loss caused by a color filter, as much as two-thirds of the total light flux in the Bayer PDs, and enables ultra-miniaturization for spatial integration. [1] However, the Foveon structure has poor detection ability for blue light, which is attributed to low absorption coefficients of Si due to its indirect transition nature. [2] A thick (≈10 µm) Si layer is required for the Foveon type because of the low absorption coefficients, which results in lengthy diffusion path, thus a low quantum efficiency in the blue region owing to severe A self-powered, color-filter-free blue photodetector (PD) based on halide perovskites is reported. A high external quantum efficiency (EQE) of 84.9%, which is the highest reported EQE in blue PDs, is achieved by engineering the A-site monovalent cations of wide-bandgap perovskites. The optimized composition of formamidinium (FA)/methylammonium (MA) increases the heat of formation, yielding a uniform and smooth film. The incorporation of Cs + ions into the FA/MA composition suppresses the trap density and increases charge-carrier mobility, yielding the highest average EQE of 77.4%, responsivity of 0.280 A W −1 , and detectivity of 5.08 × 10 12 Jones under blue light. Furthermore, Cs + improves durability under repetitive operations and ambient atmosphere. The proposed device exhibits peak responsivity of 0.307 A W −1 , which is higher than that of the commercial InGaN-based blue PD (0.289 A W −1 ). This study will promote the development of next-generation image sensors with vertically stacked perovskite PDs.

Understanding the Origin of Light Intensity and Temperature Dependence of Photodetection Properties in a MAPbBr3 Single-Crystal-Based Photoconductor

“…The stable and consistent performance of a PD over a wide light intensity range is essential for most of the photodetection applications. ,, As can be seen in Figure a, the device with 150 μm electrode spacing exhibits uniform photoresponse with attractive performance metric values under the fast optical signals compared to the device with 100 and 200 μm electrode spacings. In contrast, the performance of the MAPbBr 3 SC-based PD with the Au electrode increases with decreasing of the electrode spacing, which is consistent with the previously reported study .…”

Solution-Processed UV Photodiodes Based on Cs2Ag0.35Na0.65InCl6 Perovskite Nanocrystals

“…In 2014, Dou and co-workers demonstrated a solution-processed photodetector based on metal halide perovskite material and obtained better performance than organic and hybrid photodetectors . Since then, perovskite-based photodetectors have been developed and many exciting results have been reported due to the unique electrical and photoelectric properties of perovskites including large absorption coefficients, low exciton binding energy, and high carrier mobility. − On this basis, photodetectors based on halide perovskite have made great strides in performance enhancement and cost reduction. , Nevertheless, there are still two obstacles that hinder the application of perovskite photodetectors in human life and their commercialization in the industry: one is the instability toward moisture and heat, and another is the toxicity of lead elements. , Specifically, EU laws restrict the use of certain hazardous substances, including lead, in electrical and electronic equipment through the RoHS Directive. Hence, the RoHS-compliant device is necessary for consumer use.…”

Light outcoupling strategies in oriented perovskite light-emitting-diodes: recent trends, opportunities, and challenges toward innovation

“…The past five years have witnessed the rapid advancement of MHP by optimizing their optoelectrical properties, including high PLQY, emission color purity, tailorable bandgap, and high charge carrier mobilities to meet the internal quantum efficiency close to unity. 5,[25][26][27][28][29][30] The utilization of MHP in optoelectronic devices could eliminate the drawback associated with conventional semiconductors (e.g., organic or Cd/Zn-chalcogenides QDs). For instance, in 2009, the photovoltaic function of MHP with a power conversion efficiency of 3.8% was reported.…”