High-Detectivity UV–Vis–NIR Broadband Perovskite Photodetector Using a Mixed Pb–Sn Narrow-Band-Gap Absorber and a NiO_x Electron Blocker

Abstract

Visible and near-infrared broadband photodetectors with multispectral photosensitivity from 300 to 1100 nm were fabricated using the low-band-gap mixed Pb−Sn halide perovskites. A solution-processed nickel oxide (NiO x ) thin film was used as the electron-blocking layer in the mixed Pb−Sn low-band-gap perovskite photodetector instead of the commonly used PEDOT:PSS because NiO x has a wider band gap and a shallow conduction band edge compared to PEDOT:PSS. There is no significant difference in the film qualities such as surface roughness, grain size, and crystallinity between polycrystalline perovskite films formed on PEDOT:PSS and NiO x . A NiO x electron blocker significantly reduces (more than 100 times) the dark currents of perovskite photodetectors without sacrificing the photocurrent extraction, resulting in a 10-fold increase in detectivity. Finally, mixed Pb−Sn halide perovskite photodetectors with NiO x as an electron blocker show the detectivity value higher than 1 × 10 12 Jones from 320 to 1020 nm and the maximum detectivity value of 5 × 10 12 Jones at the peak wavelength of 940 nm. This is comparable with the detectivity values of the commercially available silicon-based visible and near-infrared broadband photodetectors.

Emerging Opportunities in Lead-Free and Lead–Tin Perovskites for Environmentally Viable Photodetector Applications

“…Variations in the crystal structure and bandgap tunability enable the use of Sn and Sn–Pb perovskites in photodetectors in the NIR, visible, and UV ranges. ,− Due to the solution and low-temperature processability, it is feasible to render flexibility, which is uncommon in traditional photodetectors that are mainly fabricated by growing inorganic semiconductor materials on a wafer using high-temperature epitaxial growth methods. Flexible photodetectors can be bent, rolled, folded, or even stretched in a variety of applications, such as wearable devices, e-skin, smart textiles, and artificial electronic eyes. ,,, Owing to the remarkable optoelectronic properties of perovskites, enhanced photodetectors can operate under low or even zero external bias in self-powered applications.…”

“…In addition to these advantages, the bandgap of perovskites can be readily tuned from ultraviolet (UV) to near-infrared (NIR) by varying the chemical composition (Figure a). These unique properties, along with the long charge carrier diffusion length, high absorption coefficient, direct bandgap, high carrier mobility, tunable optical absorption coefficient, and low exciton binding energy of PSKs, meet all the prerequisites of next-generation photodetectors. − Perovskite-based photodetectors also benefit from existing technologies developed for other solar cells and LEDs, namely, structural components and kinetic mechanisms that are common to existing optoelectronics. Therefore, perovskites have attracted enormous attention in photodetector applications. − …”

Ultrafast and Ultrabroadband UV–vis-NIR Photosensitivity under Reverse and Self-Bias Conditions by n+-ZnO/n-Si Isotype Heterojunction with >1 kHz Bandwidth

“…Photodetectors have a wide range of applications in sensing, communication systems, imaging, environment monitoring, etc. − Depending upon the energy corresponding to the band gap values, different semiconductor materials operate in different spectral regions. In contrast to narrow band photodetectors, broadband photodetectors have gained attention in various applications due to their photodetection ability of a single device in a wide spectral range from ultraviolet (UV) to infrared (IR). − Silicon (Si) is considered one of the most preferable photodetectors in the near-infrared (NIR) to visible region. , However, Si-based photodetectors have limitations of large dark current, low absorption and large reflection, low responsivity, and less efficiency. − Heterojunction of Si with wide band gap materials would overcome these limitations. , An aniso-type p-n heterojunction is well established; however, on the other hand, an iso-type heterojunction has not been explored comprehensively. Isotype heterojunctions have similar majority carriers which contribute to the currents. , As the mobility of holes is much less, a p-p isotype heterojunction is not preferable for high-speed photodetector, whereas a n-n heterojunction would be fruitful.…”

Upconverting Near‐Infrared Light Detection in Lead Halide Perovskite with Core–Shell Lanthanide Nanoparticles

“…[11][12][13][14][15] However, only a limited region of light (i.e., <800 nm visible light) can be detected due to the bandgap in these materials. It is possible to extend the detection wavelength to the NIR region by replacing Pb 2þ with Sn 2þ to narrow the bandgap; [16][17][18][19][20] however, many issues such as significant decrease in thermal stability and lower photoelectric conversion efficiency in tin-than lead-based devices have been encountered.In this study, a new NIR detection method for lead halide perovskites by the use of upconversion (UC) materials, which can convert NIR light to visible light, is presented. High optical absorption coefficients (10 5 cm À1 ) of lead halide perovskites enable efficient detection of visible light on perovskite-based photodetectors.…”

“…[11][12][13][14][15] However, only a limited region of light (i.e., <800 nm visible light) can be detected due to the bandgap in these materials. It is possible to extend the detection wavelength to the NIR region by replacing Pb 2þ with Sn 2þ to narrow the bandgap; [16][17][18][19][20] however, many issues such as significant decrease in thermal stability and lower photoelectric conversion efficiency in tin-than lead-based devices have been encountered.…”