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Narrowband photodetectors have broad application prospects in many fields where only a range of specific wavelengths of light needs to be detected. However, the current narrowband detectors have some disadvantages, such as the integration is difficult, the full width at half-maximum is not narrow enough, and the spectral rejection ratio is not ideal (≤20). Here, we present a self-filtering photodetector based on MAPbX3 single crystals with a very narrow spectral response and a full width of 15 nm at half maximum. It also shows a high responsivity (∼100 mA/W) and a high spectral rejection ratio (∼300). What is more, the response spectrum can be tuned within a certain range (from 440 to 560 nm) by varying the halide composition and thus its bandgap. This provides a new design paradigm for self-filtering narrowband photodetectors. [ABSTRACT FROM AUTHOR]

Narrowband photodetection provides important information in a specific wavelength range. Specially, the use of nonoptical‐filter narrowband photodetectors based on MAPbX3 (MA = CH3NH3; X = Cl, Br, I) perovskites is reported of great potential. However, current MAPbX3‐based narrowband photodetectors have to sacrifice their photocurrent and response speed to achieve an acceptable spectral rejection ratio. In this work, a new type of heterojunction photodetector (hetero‐PD) with a structure of (n‐type doped MAPbCl3)/(intrinsic MAPbBr2.5Cl0.5)/(n‐type doped MAPbBr3) via epitaxial growth is demonstrated as a narrowband photodetector. Through optical bandgap engineering, photons with different wavelength can be absorbed in different layers. Owing to the n–i–n energy band structure, most external bias would apply on a tiny region near the n–i heterojunction. Besides, the energy barriers in the heterojunctions can block holes from injection and collection, resulting in low‐noise electron‐only hetero‐PDs. By sufficiently suppressing the background noise from short‐wavelength photons, hetero‐PDs are capable of achieving a high spectral rejection ratio of 98.1% under an electrical field of 8 V cm−1. Moreover, hetero‐PDs exhibit a high external quantum efficiency value of 45%, a narrow full width at half‐maximum of 13 nm, and a response time of 1.35 µs. [ABSTRACT FROM AUTHOR]

Perovskite single crystals (PSCs) can be used to fabricate high performance photoelectric detectors due to their superior optoelectronic characteristics. Generally, an external electric field needs to be applied in PSC-based detectors to improve their charge collection efficiency. However, the large external electric field increases the dark current, which will enlarge the noise current. To alleviate this drawback, an approach of fabricating a PSC-based heterojunction is proposed in this work, which contributes to reduced dark current in a relatively high reverse electric field. In this study, a heterojunction formed by epitaxially growing MAPbBr3 PSCs on Bi3+-doped MAPbCl3 PSCs is reported, and it shows relatively low trap density and higher built-in potential. The as-fabricated Au-MAPbBr3/Bi3+-doped MAPbCl3 PSC heterojunction-Au photodiode shows smaller dark current density, better long-term current stability and reduced noise level by approximately four orders compared to the Au–MAPbBr3 PSCs–Au photoconductor device under an external reverse voltage of 100 V (mean electric field of ∼31.5 V mm−1). Moreover, the pN heterojunction photodiode shows favorable X-ray detection performance, with a fast response time of 4.89 μs and high sensitivity of 1.72 × 103 μC Gyair−1 cm−2 for 50 kVp X-ray photons under a reverse electric field of 31.5 V mm−1. This work confirms that the epitaxial fabrication of PSC heterojunctions may be a promising strategy to enhance the performance of X-ray photodetectors. [ABSTRACT FROM AUTHOR]

• The double cation halide perovskite MACsPbBr 3 embedded in polymers constitute the film with improved surface coverage, surface passivation, light absorption, stability, and charge carrier lifetime. • The introduction of AuNPs enhances the light absorption and extraction efficiency of carriers to further enhance the device performance. • The incorporation of MAPbBr 3 -Pero+PVDF in CsPbBr 3 -Pero increased surface coverage with and a large number of smooth crystals surrounded by MA-Pero+PVDF crystal, which decreased surface roughness to provide better interfacial contact with the top electrode. • The addition of PVDF polymer reduced dark current the photocurrent and the addition of PVP improved uniform dispersivity as compared to PEO and improved photocurrent. • The optimized plasmonic enhanced MACsPbBr 3 -polymer-based PD has achieved a high photo-to-dark current ratio, responsivity, and specific detectivity >106, 55.91 AW−1, and 7.91×1014 Jones, which is 1.12-fold and 10-folds greater than that for the no-plasmonic device. Organic-inorganic hybrid perovskite is being extensively applied to optoelectronics. However, the complex fabrication techniques, long-term instability, inefficient charge transportation; poor surface coverage hinders the expansion of its applications. Herein, we report for the first time the in-situ synthesis of MACsPbBr 3 -perovskite crystals in polymer-matrix to act as a light absorber for efficient ultraviolet light detection. The devices fabricated with the MACsPbBr 3 -perovskite films showed a maximum photocurrent of 8.9 × 10−6, a dark current of 1.7 × 10−11 A, responsivity of 45.75 AW−1, detectivity of 1.05 × 1013 Jones and on/off ratio >105 at 0 V, under the illumination of 0.28 mW cm−2. The plasmonic enhancement was explored by fabricating PDs on (gold nanoparticles) AuNPs/ZnO structure, which exhibited photocurrent enhancement (10−5), ascribed to the huge localized electric field induced by the surface plasmon resonance, scattering, and reflectance from AuNPs and structured ZnO surface, and improved the responsivity (55.91 AW−1) and on/off ration (>106) by 1.12-fold and 10-fold. And the formed Schottky barrier between Pero and AuNPs/ZnO region could lead to the reduced dark current (10−13 A) and improved detectivity (7.91 × 1014 Jones). This study offers a different pathway for the designing of high-performance plasmonic PDs. We have utilized MACsPbBr 3 +PVDF+PVP (Pero+Polymer) composite film for efficient UV-photo detection. Also, we have employed the same composite film to investigate plasmonic enhanced photodetector. The addition of MA-Pero in the PVDF matrix not only improves the surface coverage but also reduces the dark current due to PVDF. MA-Pero+PVDF combined with Cs-Pero+PVP overall improves surface coverage, surface passivation, UV-light absorption, stability, and charge carrier lifetime. Preparing this composite film on the structured layer of AuNPs/ZnO improves not only absorption but the carrier transportation in the Pero-polymer composite film to enhance the detection and response of photodetector due to the additional effect of scatterings, reflectance, and electric field enhancement. Such photodetector provides efficient photodetection at 410 nm as compared to conventional perovskite film. [Display omitted] [ABSTRACT FROM AUTHOR]