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1.
    
2D perovskites have attracted intensive attention by virtue of their excellent optical and electrical properties along with good stabilities. Herein, a highly sensitive self-powered photodiode based on (PEA)2(MA)4Pb5I16 (PEA=C6H5(CH2)NH3, MA=CH3NH3) 2D perovskite is demonstrated by dual interface passivations. The Al2O3 bottom passivation can reduce the pinhole defects in the 2D perovskite film and suppress the trap-related recombination loss, bringing forward much reduced dark current and increased photocurrent. The poly (methyl methacrylate) (PMMA) top passivation can encapsulate the 2D perovskite film and thus improve the stability of the device. These results show that the 2D perovskite-based photodiode with dual interface passivations exhibits a large photo-to-dark current ratio of 107, a fast response speed of 597 ns and a linear dynamic range of 160 dB without bias. Responsivity (R) and detectivity (D*) respectively reach 0.36 A W−1 and 5.4 × 1012 Jones under 532 nm laser illumination at a power density of 1.5 nW cm−2. Moreover, the dual interface passivated device exhibits good stabilities. This study paves the road for developing low-cost, low-power, solution processed image sensors.  相似文献   

2.
    
2D Ruddlesden–Popper perovskites have attracted increasing attention for their outstanding optoelectronic properties and improved stability compared to the 3D counterparts. The unique nature of the crystal growth orientations and the uneven distribution in the 2D perovskites provide a great opportunity to construct a promising lateral photodetector device that has not been fully uncovered. Here, by improving the random orientation to the vertical orientation of the film in the lateral device structure, the dark current is expected to be significantly suppressed in the photodetector. Accompanied by the gradient phase distribution, a p-type conductive channel at the bottom and another electron collection layer on the top are applied to achieve a high on/off ratio. Overall, the resultant photodetector realizes a low dark current of 10−10 A and exhibits impressive photodetection performance, including a high responsivity of 10.10 A W−1, a notable detectivity of 6.83 × 1012 Jones, and fast response speeds (14 ms/31 ms).  相似文献   

3.
    
Layered (2D) perovskites are an emerging attractive 2D system with enhanced stability to ambient conditions as opposed to their highly unstable three dimensional bulk counterpart. Their uniquely tuneable optical and electrical properties are underpinning a surge of interest in 2D-photovoltaics. So far, the development of nano-scale integrated opto-electronic 2D perovskite devices remains nearly unexplored since they have generally been found to be incompatible with standard top-down semiconductor nano-fabrication technologies. Here, following the synthesis of solvent-stable 2D-fluorinated phenethylammonium lead iodide perovskite (F-PEA)2PbI4 (F-PEAI), planar photodetectors entirely fabricated in atmosphere is demonstrated, exhibiting figures of merit rivalling those of commercial silicon photodiodes. A record large room temperature detectivity (>5 × 1017 Jones), a fast time photoresponse (rise time 1.5 ns), an extraordinarily large linear dynamic range (228 dB), as well as a photo-responsivity of ≈ 1100 AW−1 are demonstrated for devices on a range of substrates including flexible wearable media without the need for any planarization or any atomically thin dielectric, in stark contrast to other 2D semiconductors. Finally, the suitability of nano-scale 2D F-PEAI photodetector arrays with sub-wavelength pixel size of just 100 nm of use for high definition imaging is demonstrated.  相似文献   

4.
    
Recently lead halide perovskite based solar cells have rapidly advanced and their power conversion efficiency (PCE) increased to 25.7%. The progress has been attributed to the super-long carriers’ lifetime (τ) and long diffusion length (LD) of the photocarriers, however it has been a challenge to precisely characterize and understand the super-long τ and LD of photocarriers. Here, a MAPbI3 single crystal exhibits four different τ which increase with LD extending from nm scale to mm scale. The prior two lifetimes estimated by transient photoluminescence (TPL) spectra are in the range of ns which comes from the recombination of photocarriers in the tens of nm thick surface layer. In contrast, the third lifetime estimated by transient open-circuit voltage is hundreds of µs, which is a result of the excess photocarriers diffusing hundreds of µm to electrodes. Finally, the fourth lifetime estimated from the transient photoconductance is as long as sub-second since the low-density photocarriers under an electric field drift across the mm-scale high-quality single crystal. This study not only clarifies the physical mechanisms of four different lifetimes of photocarriers but also facilitates the design of novel electronics with the halide perovskite semiconductors.  相似文献   

5.
    
Methylammonium lead iodide (MAPbI3) perovskite is manipulated through an additional organic‐solvent‐rinsing process during an intermediate film fabrication stage. This additional process includes low‐temperature preannealing following by rinsing the films using isobutyl alcohol (IBA) before final annealing. This partially dissolves the small crystals in the perovskite intermediate and reduces nucleation density. The small crystals recrystallize into larger sizes via a dissolution–crystallization mechanism, leading to a reduction in the grain boundaries and interfacial defects. Preannealing is also crucial in solubility control and for tuning the crystallization. Crystal‐size‐dependent optical band gaps may be attributed to a weak quantum confinement effect. Excess PbI2 residue is induced at the perovskite surface thanks to the selective solubility of IBA, which improves the passivation of the perovskite surface. A synergistic improvement in grain size and in PbI2 residue leads to substantial enhancement in device performance. The power conversion efficiency of an optimized photovoltaic device reaches 18.47%, which is more than a 15% increase compared to a control device.  相似文献   

6.
    
Both photodetectors (PDs) and optoelectronic synaptic devices (OSDs) are optoelectronic devices converting light signals into electrical responses. Optoelectronic devices based on organic semiconductors and halide perovskites have aroused tremendous research interest owing to their exceptional optical/electrical characteristics and low-cost processability. The heterojunction formed between organic semiconductors and halide perovskites can modify the exciton dissociation/recombination efficiency and modulate the charge-trapping effect. Consequently, organic semiconductor/halide perovskite heterojunctions can endow PDs and OSDs with high photo responsivity and the ability to simulate synaptic functions respectively, making them appropriate for the development of energy-efficient artificial visual systems with sensory and recognition functions. This article summarizes the recent advances in this research field. The physical/chemical properties and preparation methods of organic semiconductor/halide perovskite heterojunctions are briefly introduced. Then the development of PDs and OSDs based on organic semiconductor/halide perovskite heterojunctions, as well as their innovative applications, are systematically presented. Finally, some prospective challenges and probable strategies for the future development of optoelectronic devices based on organic semiconductor/halide perovskite heterojunctions are discussed.  相似文献   

7.
    
Hybrid organic–inorganic lead halide perovskite single crystal thin film (SCTF) recently has attracted enormous interest in the field of optoelectronic devices, since it efficiently resolves the trade‐off between thickness and carrier diffusion length. However, the toxicity of lead element and the instability induced by organic component still hinder its future developments. In this work, lead‐free all‐inorganic Cs3Bi2I9 SCTF with a high orientation along (00h) has been in situ grown on indium tin oxide (ITO) glass via a space‐limited solvent evaporation crystallization method. The trap density of Cs3Bi2I9 SCTF (5.7 × 1012 cm?3) is 263 folds lower than that of the polycrystalline thin film (PCTF) counterpart, together with a 5‐order‐of‐magnitude higher carrier mobility. These superior charge transfer properties enable a photoresponse on–off ratio as high as 11 000, which far surpasses that of the PCTF device by 460 folds, comparable to the lead halide perovskite. Furthermore, the Cs3Bi2I9 SCTF photodetector exhibits outstanding stability even without any encapsulation, whose initial performance is well maintained after aging 1000 h in humid air of 50% RH or continuous on–off light illumination for 20 h. This work will pave the way to produce new families of high‐performance, stable, and nontoxic perovskite SCTF for future optoelectronic applications.  相似文献   

8.
Solution-processed narrow-bandgap Sn–Pb perovskites have shown their potential in near-infrared (NIR) photodetection as a promising alternative to traditional silicon and inorganic compounds. To achieve efficient NIR photodetection, high-quality Sn–Pb perovskite thick films with well-packed, smooth, and pinhole/void-free features are highly desirable for boosting the spectral absorption. Understanding the crystallization kinetics and tuning the crystallization are fundamentally important to reach such high-quality thick Sn–Pb perovskite films, and have been limitedly explored. Herein, an approach of double-side crystallization tuning through low-temperature space-restricted annealing in methylammonium-free Sn–Pb perovskite films with over 1 µm thickness is proposed. More specifically, through simultaneously retarding the crystallization in the top of precursor films and promoting the crystal growth of the bottom of precursor films, high-quality and block-like thick FA0.85Cs0.15Sn0.5Pb0.5I3 perovskite films with improved crystallinity, preferred out-of-plane orientation, and reduced trap density are achieved. Finally, photovoltaic-mode Sn–Pb perovskite NIR photodetectors show a high external quantum efficiency of ≈80% at 760–900 nm, a recorded responsivity of 0.53 A W−1, and a high specific detectivity of 6 × 1012 Jones at 940 nm. This study offers the fundamental understanding of the crystallization kinetics of thick perovskite films and paves the way for perovskite-based emerging NIR photodetection and imaging applications.  相似文献   

9.
    
Lead halide perovskites (LHPs) have been widely investigated in photodetection applications owing to their intriguing optoelectronic properties. However, the application of LHPs-based photodetectors (PDs) is hindered because of the toxicity of lead and instability in ambient air. Here, an air-stable self-powered photodetector is designed based on all-inorganic lead-free CsBi3I10/SnO2 heterojunction. The device exhibits broad spectral response in both UV and visible light, fast response on µs scale, and decent long-term stability. The device holds a faster response speed (tr/td = 7.8/8.8 µs), among the best reported self-powered lead-free perovskites photodetectors. More importantly, the device can display obvious photoresponses even under ultra-weak light intensity as low as 10 pW cm–2, showing better weak-light sensitivity than previously reported lead-free perovskites photodetectors, to the best of our knowledge. Moreover, the device holds good air stability in the 73 days test without encapsulation. These results suggest that CsBi3I10/SnO2-based self-powered PDs with high photodetection capability possess enormous potential in stable and broadband PDs for weak light detection in the future.  相似文献   

10.
    
Fibrous photodetectors (FPDs) have attracted great interest in wearable and consumer electronics, which is a lightweight and flexible tools to achieve efficient light information transmission. However, there is a necessary compromise between high optoelectronic performance and high-level integration. Herein, a woven optoelectronic keyboard consisting of 40 PD button units is extended and integrated from four individual FPDs, with the integration level expanding by 1000%. Each FPD is based on uniform type-II TiO2/Cs3Cu2I5 heterojunction, which exhibits greatly reduced dark current by eight orders of magnitudes, large rectification ratio up to 33306@± 5V, high on–off ratio of 2.8 × 104@−1 V and self-powered responsivity of 26.9 mA W−1. The vacuum-deposited Cs3Cu2I5 nanoparticles finely passivate the massive defects and serve as a p-type hole transport layer to improve hole transfer efficiency, which greatly promotes the radial transport and collection of photogenerated electrons. Moreover, the photocurrent remains highly stable after bending and twisting states. Intriguingly, the woven optoelectronic keyboards successfully realize logic AND/OR, further identifying the UV light signal as a keying text signal (“A–Z” letters, “0–9” numbers, and four punctuations). This work not only provides a scalable strategy to reduce device redundancy but also shows the great potential of fibrous photodetectors for wearable optical communication.  相似文献   

11.
    
Perovskite photodetectors are fabricated via structuring a perovskite/organic heterojunction with CH3NH3PbI3 and a high‐mobility and stable organic semiconductor dioctylbenzothieno [2,3‐b] benzothiophene (C8BTBT), which possess broad range photoresponse from ultraviolet to near‐infrared, fast response, and excellent stability. The CH3NH3PbI3/C8BTBT heterojunction photodetectors exhibit an excellent ratio of photocurrent to dark current, I light/I dark, as high as 2.4 × 104, a high responsivity up to 24.8 AW−1, and a fast response of about 4.0 ms. Meanwhile, the photodetectors can maintain 90% performance even exposed in ambient condition without encapsulation for 20 d. In addition, the detailed mechanism is disclosed based on ultraviolet photoemission spectroscopy, steady‐state photoluminescence (PL) spectra, and PL lifetime experiments. The C8BTBT layer acts as an efficient hole‐extraction layer to let the holes quickly transport to the electrodes due to its perfect filling in the gaps between perovskite grains, as well as its intrinsic high mobility and the energy‐level match with the CH3NH3PbI3. The stable C8BTBT layer can well play as a waterproof layer as well to prevent the perovskite CH3NH3PbI3 from the degradation. The research provides an excellent method for fabricating high‐performance and stable perovskite photodetectors using perovskite/organic heterojunction.  相似文献   

12.
    
Methylammonium lead iodide (MAPbI3) perovskite has garnered significant interest as a versatile material for optoelectronic applications. The temperature-dependent photoluminescence (TDPL) and phase-transition behaviors revealed in previous studies have become standard indicators of defects, stability, charge carrier dynamics, and device performance. However, published reports abound with examples of irregular photoluminescence and phase-transition phenomena that are difficult to reconcile, posing major challenges in the correlation of those properties with the actual material state or with the subsequent device performance. In this paper, a unifying explanation for the seemingly inconsistent TDPL and phase-transition (orthorhombic-to-tetragonal) characteristics observed for MAPbI3 is presented. By investigating MAPbI3 perovskites with varying crystalline states, ranging from polycrystal to highly oriented crystal as well as single-crystals, key features in the TDPL and phase-transition behaviors are identified that are related to the extent of crystal domain-size-dependent residual stress and stem from the considerable volume difference (ΔV ≈ 4.5%) between the primitive unit cells of the orthorhombic (at 80 K) and tetragonal phases (at 300 K) of MAPbI3. This fundamental connection is essential for understanding the photophysics and material processing of soft perovskites.  相似文献   

13.
    
2D layered van der Waals (vdW) atomic crystals are an emerging class of new materials that are receiving increasing attention owing to their unique properties. In particular, the dangling‐bond‐free surface of 2D materials enables integration of differently dimensioned materials into mixed‐dimensional vdW heterostructures. Such mixed‐dimensional heterostructures herald new opportunities for conducting fundamental nanoscience studies and developing nanoscale electronic/optoelectronic applications. This study presents a 1D ZnO nanowire (n‐type)–2D WSe2 nanosheet (p‐type) vdW heterojunction diode for photodetection and imaging process. After amorphous fluoropolymer passivation, the ZnO–WSe2 diode shows superior performance with a much‐enhanced rectification (ON/OFF) ratio of over 106 and an ideality factor of 3.4–3.6 due to the carbon–fluorine (C? F) dipole effect. This heterojunction device exhibits spectral photoresponses from ultraviolet (400 nm) to near infrared (950 nm). Furthermore, a prototype visible imager is demonstrated using the ZnO–WSe2 heterojunction diode as an imaging pixel. To the best of our knowledge, this is the first demonstration of an optoelectronic device based on a 1D–2D hybrid vdW heterojunction. This approach using a 1D ZnO–2D WSe2 heterojunction paves the way for the further development of electronic/optoelectronic applications using mixed‐dimensional vdW heterostructures.  相似文献   

14.
    
Perovskites have attracted intensive attention as promising materials for the application in various optoelectronic devices due to their large light absorption coefficient, high carrier mobility, and long charge carrier diffusion length. However, the performance of the pure perovskite nanocrystals-based device is extremely restricted by the limited charge transport capability due to the existence of a large number of the grain boundary between perovskite nanocrystals. To address these issues, a high-performance photodetector based on all-inorganic CsPbBr3 perovskite nanocrystals/2D non-layered cadmium sulfide selenide heterostructure has been demonstrated through energy band engineering with designed typed-II heterostructure. The photodetector exhibits an ultra-high light-to-dark current ratio of 1.36 × 105, a high responsivity of 2.89 × 102 A W−1, a large detectivity of 1.28 × 1014 Jones, and the response/recovery time of 0.53s/0.62 s. The enhancement of the optoelectronic performance of the heterostructure photodetector is mainly attributed to the efficient charge carrier transfer ability between the all-inorganic CsPbBr3 perovskites and 2D cadmium sulfide selenide resulting from energy band alignment engineering. The charge carriers’ transfer dynamics and the mechanism of the CsPbBr3 perovskites/2D non-layered nanosheets interfaces have also been studied by state-state PL spectra, fluorescence lifetime imaging microscopy, time-resolved photoluminescence spectroscopy, and Kelvin probe force microscopy measurements.  相似文献   

15.
    
Halide perovskite like methylammonium lead iodide perovskite (MAPbI3) with its prominent optoelectronic properties has triggered substantial concerns in photocatalytic H2 evolution. In this work, to attain preferable photocatalytic performance, a MAPbI3/cobalt phosphide (CoP) hybrid heterojunction is constructed by a facile in situ photosynthesis approach. Systematic investigations reveal that the CoP nanoparticle can work as co‐catalyst to not only extract photogenerated electrons effectively from MAPbI3 to improve the photoinduced charge separation, but also facilitate the interfacial catalytic reaction. As a result, the as‐achieved MAPbI3/CoP hybrid displays a superior H2 evolution rate of 785.9 µmol h?1 g?1 in hydroiodic acid solution within 3 h, which is ≈8.0 times higher than that of pristine MAPbI3. Furthermore, the H2 evolution rate of MAPbI3/CoP hybrid can reach 2087.5 µmol h?1 g?1 when the photocatalytic reaction time reaches 27 h. This study employs a facile in situ photosynthesis strategy to deposit the metal phosphide co‐catalyst on halide perovskite nanocrystals to conduct photocatalytic H2 evolution reaction, which may stimulate the intensive investigation of perovskite/co‐catalyst hybrid systems for future photocatalytic applications.  相似文献   

16.
The development of an efficient fabrication route to achieve high-resolution perovskite pixel array is key for large-scale flexible image sensor devices. Herein, a high-resolution and stable 10 × 10 flexible PDs array based on formamidinium(FA+) and phenylmethylammonium (PMA+) quasi-2D (PMA)2FAPb2I7 (n = 2) perovskite is demonstrated by developing SiO2-assisted hydrophobic and hydrophilic treatment process on polyethylene terephthalate substrate. By introducing Au nanoparticles (Au NPs),  the perovskite film quality is improved and grain boundaries are reduced. The mechanism by which Au NPs upgrade the photoelectric quality of perovskite is mainly revealed by glow discharge-optical emission spectroscopy (GD-OES) and grazing-incidence wide-angle X-ray scattering (GIWAXS). To further improve the photoelectric performance of the devices, a post-treatment strategy with formamidinium chloride (FACl) is used . The optimized flexible PDs arrays show excellent optoelectronic properties with a high responsivity of 4.7 A W−1, a detectivity of 6.3 × 1012 Jones, and a broad spectral sensitivity. The device also exhibits excellent electrical stability even under severe bending and excellent flexural strength, as well as excellent environmental stability. Finally, the integrated flexible PDs arrays are used as sensor pixels in an imaging system to obtain high-resolution imaging patterns, demonstrating the imaging capability of the PDs arrays.  相似文献   

17.
    
2D Ruddlesden–Popper (RP) layered metal-halide perovskites have garnered significant interest due to their unique photoelectric properties and excellent stability. However, 2D perovskite films prepared via solution process generally exhibit multi-quantum well structure with random well width distribution, which significantly impedes the carrier transportation. Herein, the synthesis of phase-pure 2D (PEA)2FAPb2I7 (PEA = C8H11N, FA = CH4N2) perovskite thin films is reported in ambient environment achieved by suppressing the formation of the 3D perovskite phase. First, incorporation of MACl additive can effectively regulate the intermediate during crystallization, facilitating the formation of a metastable 3D MAxFA1-xPbIyCl3-y phase. Second, precise control of environmental humidity is employed to further inhibit the formation of α-FAPbI3 phase. As a result, the perovskite intermediate composed of predominantly metastable 3D phase and 2D n = 2 phase is achieved, which is eventually transformed into 2D n = 2 perovskite during annealing, leading to markedly enhanced phase purity. Photoconductive-type photodetectors based on the phase-pure 2D RP perovskite films are fabricated, demonstrating a high detectivity of over 9.4 × 1012 Jones due to the improved carrier transportation. This study provides a comprehensive insight into the crystallization process of phase-pure 2D perovskites.  相似文献   

18.
The cost‐effective processability and high efficiency of the organic–inorganic metal halide perovskite solar cells (PSCs) have shown tremendous potential to intervene positively in the generation of clean energy. However, prior to an industrial scale‐up process, there are certain critical issues such as the lack of stability against over moisture, light, and heat, which have to be resolved. One of the several proposed strategies to improve the stability that has lately emerged is the development of lower‐dimensional (2D) perovskite structures derived from the Ruddlesden–Popper (RP) phases. The excellent stability under ambient conditions shown by 2D RP phase perovskites has made the scalability expectations burgeon since it is one of the most credible paths toward stable PSCs. In this review, the 2D/3D mixed system for photovoltaics (PVs) is elaborately discussed with the focus on the crystal structure, optoelectronic properties, charge carrier dynamics, and their impact on the photovoltaic performances. Finally, some of the further challenges are highlighted while outlining the perspectives of 2D/3D perovskites for high‐efficiency stable solar cells.  相似文献   

19.
    
Organic-inorganic hybrid perovskite solar cells (PSCs) with unique properties exhibit their powerful competitiveness in the photovoltaic field over the past few years. However, the challenges of stability for perovskite devices limit the commercialization and further development. The 2D/3D hybrid structures combine the superior efficiency of bulk perovskites and the superior stability of layered perovskites and gradually get hotspots of the photovoltaic field. In addition, there remains a lack of comprehensive understanding and systematic summary of the function of 2D perovskite attributed to the complex nature of 2D/3D structures. Here, the latest progress of 2D/3D hybrid structures and focus on the functionality of 2D phases in mixed structures and the underlying mechanism from the perspective of their different distributions in the perovskite layer is summarized. Then, the insight and vital factors for overall improvements in the stability of 2D/3D structures are thoroughly discussed. Finally, it is expected that this review will contribute to the present challenges and future research prospects in the photovoltaic industry.  相似文献   

20.
    
Wide‐bandgap perovskite solar cells (PSCs) with optimal bandgap (Eg) and high power conversion efficiency (PCE) are key to high‐performance perovskite‐based tandem photovoltaics. A 2D/3D perovskite heterostructure passivation is employed for double‐cation wide‐bandgap PSCs with engineered bandgap (1.65 eV ≤ Eg ≤ 1.85 eV), which results in improved stabilized PCEs and a strong enhancement in open‐circuit voltages of around 45 mV compared to reference devices for all investigated bandgaps. Making use of this strategy, semitransparent PSCs with engineered bandgap are developed, which show stabilized PCEs of up to 25.7% and 25.0% in four‐terminal perovskite/c‐Si and perovskite/CIGS tandem solar cells, respectively. Moreover, comparable tandem PCEs are observed for a broad range of perovskite bandgaps. For the first time, the robustness of the four‐terminal tandem configuration with respect to variations in the perovskite bandgap for two state‐of‐the‐art bottom solar cells is experimentally validated.  相似文献   

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