Enhanced Response Speed in 2D Perovskite Oxides-Based Photodetectors for UV Imaging through Surface/Interface Carrier-Transport Modulation

Abstract

The long-time decay process induced by the persistent photoconductivity (PPC) in metal oxides-based photodetectors (PDs) impedes our demands for high-speed photodetectors. 2D perovskite oxides, emerging candidates for future high-performance PDs, also suffer from the PPC effect. Here, by integrating 2D perovskite Sr2Nb3O10 (SNO) nanosheets and nitrogen-doped graphene quantum dots (NGQDs), a unique nanoscale heterojunction is designed to modulate surface/interface carrier transport for enhanced response speed. Notably, the decay time is reduced from hundreds of seconds to a few seconds. The 4%NGQDs-SNO PD exhibits excellent performance with a photocurrent of 0.47 μA, a high on–off ratio of 2.2 × 104, and a fast pulse response speed (τ decay = 67.3 ms), making it promising for UV imaging. The trap-involved decay process plays a dominant role in determining the decay time, resulting in the PPC effect in SNO PD, and the trap states mainly originate from oxygen vacancies and chemisorbed oxygen molecules. A significantly enhanced photoresponse speed in NGQDs-SNO PDs can be ascribed to the modulated surface/interface trap states and the efficient carrier pathway provided by the nanoscale heterojunction. This work provides an effective way to enhance the response speed in 2D perovskite oxides constrained by PPC via surface/interface engineering, promoting their applications in optoelectronics.

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

“…Under 1.5 V reverse bias conditions, the photocurrent ( I P ) spectrum of the heterojunction device in a broad range of 940 to 300 nm is shown in Figure a, confirming a UV–vis–NIR broadband photoresponse with a maximum photocurrent at 470 nm. As the nature of the photocurrent spectrum is associated with the intensity spectrum of the used lamp, the responsivity ( R λ ) values have been derived using the equation: R λ = I normalp normalh P normalL normali normalg normalh normalt × A where photocurrent due to illumination I ph = | I P – I d |, A is the active area of the device and P Light is the power density of the illuminating light. The responsivity spectrum shows a maximum R λ value of ∼200 mA/W at the NIR region then it slightly decreases as we move to the visible region and it again increases below 400 nm in the UV region.…”

Ammonium Salt Assisted Crystallization for High Performance Two-Dimensional Lead-Free Perovskite Photodetector

“…Then we monitored the time-resolved photoluminescence (TRPL) of all samples to further explore the carrier transport modulated mechanism. According to the biexponential fitting, the average lifetimes are calculated to be 1.5138 and 0.5055 ns for NACF (10 mol %) and control samples, respectively , (Figure d). For other concentrations, the average lifetime are calculated to be 1.0527 ns, 1.1520 ns, and 1.0781 ns, respectively, as shown in Figure S6b.…”

Direct Z-Scheme SnSe2/SnSe Heterostructure Passivated by Al2O3 for Highly Stable and Sensitive Photoelectrochemical Photodetectors

“…Nature can always utilize the sun energy quickly and efficiently to sustain our planet. For example, the photosynthesis in green plants develops a photogenerated electron–hole migration process analogous to the letter “Z” in the sun energy management. , This photophysical and photochemical process can boost charge separation, enhance the charge transport, and increase the redox ability, which is desirable for many artificial photoelectric devices such as solar cells, photodetectors, and photoelectrochemical (PEC) devices. − Inspired by this photo-process, photocatalysis based on the Z-scheme process is artificially designed to produce hydrogen, formic acid, methane, and methanol efficiently. − In such a case, the high reduction and oxidation capability are maintained by mimicking natural photosynthesis in the direct Z-scheme heterostructure between two semiconductors . However, the early research on the Z-scheme process is mainly focused on the photocatalysis as the photocatalyst simulated photosynthesis intuitively.…”