首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 0 毫秒
1.
    
All‐inorganic halide perovskite (AIHP) is becoming one of the most promising generation materials of perovskite photovoltaics for commercialization due to its thermodynamic stability and soared efficiency. Depending on material properties, grain boundary (GB) has detrimental or beneficial effect on device photovoltaic performance. However, less attention is paid to GB behavior in AIHPs. Herein, it is concluded that the microscopic GBs are the major sites for photocarrier generation and transport, as well as the ionic pathway dominating the current hysteresis behavior in AIHP solar cells. Kelvin probe force microscopy (KPFM) measurements reveal a lower surface potential at GBs as compared to grain interiors (GIs), suggesting a significant upward band bending around GBs. Conductive atomic force microscopy (c‐AFM) measurements show a higher current flow in the vicinity of GBs, indicating enhanced carrier separation and collection taking place at GBs. Furthermore, the existence of ion motion is evidenced both by the single‐point c‐AFM measurement and voltage‐controlled KPFM measurement, which accounts for the common current hysteresis behavior in AIHP solar cells. These investigations provide an advanced understanding of the role of GBs in AIHP and further inspiration on how to optimize device performance up to the levels of organic–inorganic hybrid perovskite.  相似文献   

2.
    
  相似文献   

3.
In this work, CsPbBr3 and PbSe nanocomposites were synthesized to protect perovskite material from self-enlargement during reaction. UV absorption and photoluminescence (PL) spectra indicate that the addition of Se into CsPbBr3 quantum dots modified the electronic structure of CsPbBr3, increasing the band gap from 2.38 to 2.48 eV as the Cs:Se ratio increased to 1:3. Thus, the emission color of CsPbBr3 perovskite quantum dots was modified from green to blue by increasing the Se ratio in composites. According to X-ray diffraction patterns, the structure of CsPbBr3 quantum dots changed from cubic to orthorhombic due to the introduction of PbSe at the surface. Transmission electron microscopy and X-ray photoemission spectroscopy confirmed that the atomic distribution in CsPbBr3/PbSe composite clusters is uniform and the composite materials were well formed. The PL intensity of a CsPbBr3/PbSe sample with a 1:1 Cs:Se ratio maintained 50% of its initial intensity after keeping the sample for 81 h in air, while the PL intensity of CsPbBr3 reduced to 20% of its initial intensity. Therefore, it is considered that low amounts of Se could improve the stability of CsPbBr3 quantum dots.  相似文献   

4.
金属卤化物钙钛矿量子点(QDs)具有良好的光电性质,是一种潜在的光催化剂材料。但是,它的稳定性较差,并且电荷传输效率不足,阻碍了其在光催化领域的应用。本工作将CsPbBr3量子点装饰在二维超薄g-C3N4纳米片(UCN)上,制备了0D/2D CsPbBr3/UCN复合光催化剂。引入UCN不仅可以通过钝化CsPbBr3量子点的表面配体来提高CsPbBr3量子点的稳定性,而且两者的能带匹配还可以促进两种材料之间的电荷转移。因此,所制备的CsPbBr3/UCN异质结构比单纯的CsPbBr3量子点和UCN具有更优越的光催化性能,这为设计具有高稳定性和光催化活性的基于CsPbX3的异质结构提供了有效的策略。  相似文献   

5.
    
All‐inorganic cesium lead halide perovskite is suggested as a promising candidate for perovskite solar cells due to its prominent thermal stability and comparable light absorption ability. Designing textured perovskite films rather than using planar‐architectural perovskites can indeed optimize the optical and photoelectrical conversion performance of perovskite photovoltaics. Herein, for the first time, this study demonstrates a rational strategy for fabricating carbon quantum dot (CQD‐) sensitized all‐inorganic CsPbBr3 perovskite inverse opal (IO) films via a template‐assisted, spin‐coating method. CsPbBr3 IO introduces slow‐photon effect from tunable photonic band gaps, displaying novel optical response property visible to naked eyes, while CQD inlaid among the IO frameworks not only broadens the light absorption range but also improves the charge transfer process. Applied in the perovskite solar cells, compared with planar CsPbBr3, slow‐photon effect of CsPbBr3 IO greatly enhances the light utilization, while CQD effectively facilitates the electron–hole extraction and injection process, prolongs the carrier lifetime, jointly contributing to a double‐boosted power conversion efficiency (PCE) of 8.29% and an increased incident photon‐to‐electron conversion efficiency of up to 76.9%. The present strategy on CsPbBr3 IO to enhance perovskite PCE can be extended to rationally design other novel optoelectronic devices.  相似文献   

6.
    
FAPbI3 perovskites have garnered considerable interest owing to their outstanding thermal stability, along with near-theoretical bandgap and efficiency. However, their inherent phase instability presents a substantial challenge to the long-term stability of devices. Herein, this issue through a dual-strategy of self-assembly 3D/0D quasi-core–shell structure is tackled as an internal encapsulation layer, and in situ introduction of excess PbI2 for surface and grain boundary defects passivating, therefore preventing moisture intrusion into FAPbI3 perovskite films. By utilizing this method alone, not only enhances the stability of the FAPbI3 film but also effectively passivates defects and minimizes non-radiative recombination, ultimately yielding a champion device efficiency of 23.23%. Furthermore, the devices own better moisture resistance, exhibiting a T80 lifetime exceeding 3500 h at 40% relative humidity (RH). Meanwhile, a 19.51% PCE of mini-module (5 × 5 cm2) is demonstrated. This research offers valuable insights and directions for the advancement of stable and highly efficient FAPbI3 perovskite solar cells.  相似文献   

7.
    
Metal halide perovskite nanostructures have sparked intense research interest due to their excellent optical properties. In recent years, although the green and red perovskite light-emitting diodes (PeLEDs) have achieved a significant breakthrough with the external quantum efficiency exceeding 20%, the blue PeLEDs still suffer from inferior performance. Previous reviews about blue PeLEDs focus more on 2D/quasi-2D or 3D perovskite materials. To develop more stable and efficient blue PeLEDs, a systematic review of blue perovskite quantum dots (PQDs) is urgently demanded to clarify how PQDs evolve. In this review, the recent advances in blue PQDs involving mixed-halide, quantum-confined all-bromide, metal-doped and lead-free PQDs as well as their applications in PeLEDs are highlighted. Although several excellent PeLEDs based on these PQDs have been demonstrated, there are still many problems to be solved. A deep insight into the advantages and disadvantages of these four types of blue-emitting PQDs is provided. Then, their respective potential and issues for blue PeLEDs have been discussed. Finally, the challenges and outlook for efficient and stable blue PeLEDs based on PQDs are addressed.  相似文献   

8.
    
All‐inorganic lead halide perovskite quantum dots (IHP QDs) have great potentials in photodetectors. However, the photoresponsivity is limited by the low charge transport efficiency of the IHP QD layers. High‐performance phototransistors based on IHP QDs hybridized with organic semiconductors (OSCs) are developed. The smooth surface of IHP QD layers ensures ordered packing of the OSC molecules above them. The OSCs significantly improve the transportation of the photoexcited charges, and the gate effect of the transistor structure significantly enhances the photoresponsivity while simultaneously maintaining high I photo/I dark ratio. The devices exhibit outstanding optoelectronic properties in terms of photoresponsivity (1.7 × 104 A W?1), detectivity (2.0 × 1014 Jones), external quantum efficiency (67000%), I photo/I dark ratio (8.1 × 104), and stability (100 d in air). The overall performances of our devices are superior to state‐of‐the‐art IHP photodetectors. The strategy utilized here is general and can be easily applied to many other perovskite photodetectors.  相似文献   

9.
近年来,全无机铯铅卤化钙钛矿CsPbX3(X=Cl, Br, I)纳米晶(NCs)材料因具有长载流子寿命、强光吸收、低成本制造和带隙可调性等独特的性能已成为研究的热点,但专注于CsPbBr3纳米晶瞬态光电导的相关研究却很少。本工作通过配体辅助再沉淀法制备了CsPbBr3纳米晶体,并改进了光电导薄膜样品的制样方法和真空瞬态光电导测试装置,研究了不同温度和不同激发功率对CsPbBr3纳米晶瞬态光电导的影响。不同温度的瞬态光电导实验结果表明,在133～273K温度范围内,光生电流衰减速率随着温度增加而逐渐减小,而在273～373 K温度范围内,光生电流衰减速率随着温度升高而逐渐增大。不同激发功率的瞬态光电导实验表明,激发功率从200mW逐渐增大到1000mW时,光生电流衰减速率增大。本工作的研究方法为研究光激发光生载流子的动力学相关行为提供了一个的新思路。  相似文献   

10.
    
The stability and optoelectronic device performance of perovskite quantum dots (Pe‐QDs) are severely limited by present ligand strategies since these ligands exhibit a highly dynamic binding state, resulting in serious complications in QD purification and storage. Here, a “Br‐equivalent” ligand strategy is developed in which the proposed strong ionic sulfonate heads, for example, benzenesulfonic acid, can firmly bind to the exposed Pb ions to form a steady binding state, and can also effectively eliminate the exciton trapping probability due to bromide vacancies. From these two aspects, the sulfonate heads play a similar role as natural Br ions in a perfect perovskite lattice. Using this approach, high photoluminescence quantum yield (PL QY) > 90% is facilely achieved without the need for amine‐related ligands. Furthermore, the prepared PL QYs are well maintained after eight purification cycles, more than five months of storage, and high‐flux photo‐irradiation. This is the first report of high and versatile stabilities of Pe‐QD, which should enable their improved application in lighting, displays, and biologic imaging.  相似文献   

11.
    
Inorganic halide perovskite quantum dots (IHPQDs) have recently emerged as a new class of optoelectronic nanomaterials that can outperform the existing hybrid organometallic halide perovskite (OHP), II–VI and III–V groups semiconductor nanocrystals, mainly due to their relatively high stability, excellent photophysical properties, and promising applications in wide‐ranging and diverse fields. In particular, IHPQDs have attracted much recent attention in the field of photoelectrochemistry, with the potential to harness their superb optical and charge transport properties as well as spectacular characteristics of quantum confinement effect for opening up new opportunities in next‐generation photoelectrochemical (PEC) systems. Over the past few years, numerous efforts have been made to design and prepare IHPQD‐based materials for a wide range of applications in photoelectrochemistry, ranging from photocatalytic degradation, photocatalytic CO2 reduction and PEC sensing, to photovoltaic devices. In this review, the recent advances in the development of IHPQD‐based materials are summarized from the standpoint of photoelectrochemistry. The prospects and further developments of IHPQDs in this exciting field are also discussed.  相似文献   

12.
    
Halide perovskites (HPs) have gained significant interest in the scientific and technological sectors due to their unique optical, catalytic, and electrical characteristics. However, the HPs are prone to decomposition when exposed to air, oxygen, or heat. The instability of HP materials limits their commercialization, prompting significant efforts to address and overcome these limitations. Transition metal dichalcogenides, such as MoS2, are chemically stable and are suitable for electronic, optical, and catalytic applications. Moreover, it can be used as a protective media or shell for other nanoparticles. In this study, a novel CsPbBr3@MoS2 core–shell nanostructure (CS-NS) is successfully synthesized by enveloping CsPbBr3 within a MoS2 shell for the first time. Significant stability of CS-NSs dispersed in polar solvents for extended periods is also demonstrated. Remarkably, the hybrid CS-NS exhibits an absorption of MoS2 and quenching of the HP's photoluminescence, implying potential charge or energy transfer from HPs to MoS2. Using finite difference time domain simulations, it is found that the CS-NSs can be utilized to produce efficient solar cells. The addition of a MoS2 shell enhances the performance of CS-NS-based solar cells by 220% compared to their CsPbBr3 counterparts. The innovative CS-NS represents important progress in harnessing HPs for photovoltaic and optoelectronic applications.  相似文献   

13.
    
Surface ligand management plays an essential role in improving the stability of perovskite quantum dots (QDs) and endowing them with novel property. Herein, a red fluorescence porphyrin-thiol (named Por-SH) is applied to adjust the surface and stimuli responsiveness of CsPbBr3 QDs. According to the theoretical and experimental results, Por-SH can bind tightly to the exposed Pb of CsPbBr3 QDs, thus leading to the formation of Por-SH-QDs with an excellent resistance to water and UV light. Moreover, CsPbBr3 act as energy donors to improve the photoresponse of Por-SH through energy transfer, especially when heated. Notably, the Por-SH and QDs behave differently in terms of response to the temperature in the Por-SH-QDs system. Therefore, the Por-SH-QDs are capable of reversible stimuli–response property in the presence of heat/cool stimuli when excited by UV light. Finally, the disposable or reversible optical encoding label based on Por-SH-QDs and QDs is obtained by combining stability and the responsiveness to stimuli. Through the selection of suitable ligands, the surface of QDs is efficiently managed, which can not only mitigate instability but also endow perovskite QDs with the responsiveness to stimuli.  相似文献   

14.
    
Stimulated emission depletion (STED) nanoscopy is one of the most promising super‐resolution imaging techniques for microstructure imaging. Commercial CdSe@ZnS quantum dots are used as STED probes and ≈50 nm lateral resolution is obtained. Compared with other quantum dots, perovskite CsPbBr3 nanoparticles (NPs) possess higher photoluminescence quantum yield and larger absorption cross‐section, making them a more effective probe for STED nanoscopy. In this study, CsPbBr3 NPs are used as probes for STED nanoscopy imaging. The fluorescence intensity of the CsPbBr3 sample is hardly weakened at all after 200 min irradiation with a 39.8 mW depletion laser, indicating excellent photobleaching resistance of the CsPbBr3 NPs. The saturation intensity of the CsPbBr3 NPs is extremely low and estimated to be only 0.4 mW (0.126 MW cm?2). Finally, an ultrahigh lateral resolution of 20.6 nm is obtained for a single nanoparticle under 27.5 mW STED laser irradiation in CsPbBr3‐based STED nanoscopy imaging, which is a tenfold improvement compared with confocal microscopy. Because of its high fluorescence stability and ultrahigh resolution under lower depletion power, CsPbBr3‐assisted STED nanoscopy has great potential to investigate microstructures that require super‐resolution and long‐term imaging.  相似文献   

15.
    
For the application of quantum dots (QDs) on next‐generation displays, it is of significant importance to improve QDs patterning technology. Here, this paper reports a simple and fast approach of perovskite QDs patterning based on laser direct writing (LDW). It is a mask‐free and programmable method, including three steps: spin‐coating perovskite QDs, laser writing, and solvent washing. The LDW patterning on QDs relies on the removal of surfactant around the QDs by laser scanning. Macroscopic QD patterns are composed of many microscale QD lines formed via laser scanning. The width and morphology of QD lines can be controlled by varying LDW parameters, including the laser spot size, scanning speed, and laser energy, which also leads to the variation of QDs brightness. Moreover, a large‐scale (100 mm × 100 mm) patterning is demonstrated by LDW, which implies its great potential for large area display application.  相似文献   

16.
    
Inorganic halide perovskite quantum dots (IPQDs) hold great potentials for wide color gamut displays due to their high quantum yield, narrow, and composition‐tunable emissions. However, they are facing a big challenge to narrower size distribution and upscalable synthesis procedure. Here, different from the usual spontaneous nucleation, a one‐pot strategy, simply aided by uniformly heterogeneous nucleation agents, achieving mass production (≈1.8 g) with high product yield within short reaction time for various IPQDs is demonstrated. This method not only avoids the use of polar solvents, but also averts desirable transfer or injection operations. The heterogeneous nucleation takes place at surface chemical inert materials, which provide additional spatial separation effect, inhibiting the aggregative regrowth of primary IPQDs and thus enabling homogeneous nucleation and growth for various IPQDs. As a result, highly uniform IPQDs, as well as higher color purity, are achieved. Impressively, CsPbBr3 QD dispersion exhibits ultranarrow full width at half maximum of 15.5 nm. Overall, through the novel strategy, blue, green, and red light‐emitting diodes (LEDs) achieved with good optical properties contribute to a color gamut of 140% of the National Television System Committee standard, which is among the widest color gamut in the field of QLED and hence significant for the future high‐definition display.  相似文献   

17.
    
To evaluate the role of planar defects in lead‐halide perovskites—cheap, versatile semiconducting materials—it is critical to examine their structure, including defects, at the atomic scale and develop a detailed understanding of their impact on electronic properties. In this study, postsynthesis nanocrystal fusion, aberration‐corrected scanning transmission electron microscopy, and first‐principles calculations are combined to study the nature of different planar defects formed in CsPbBr3 nanocrystals. Two types of prevalent planar defects from atomic resolution imaging are observed: previously unreported Br‐rich [001](210)∑5 grain boundaries (GBs) and Ruddlesden–Popper (RP) planar faults. The first‐principles calculations reveal that neither of these planar faults induce deep defect levels, but their Br‐deficient counterparts do. It is found that the ∑5 GB repels electrons and attracts holes, similar to an n–p–n junction, and the RP planar defects repel both electrons and holes, similar to a semiconductor–insulator–semiconductor junction. Finally, the potential applications of these findings and their implications to understand the planar defects in organic–inorganic lead‐halide perovskites that have led to solar cells with extremely high photoconversion efficiencies are discussed.  相似文献   

18.
Carbon pre-deposition onto the bare Si(001) surface has been shown to alter the (2×1) surface structure by formation of c(4×4) reconstructed domains containing a high C-concentration. Here we studied by ultra-high vacuum scanning tunneling microscopy the effect of this restructured surface on the initial stages of Ge nucleation by molecular beam epitaxy. Ge is found to form three-dimensional (3D) islands already at sub-monolayer coverage, resulting in a Volmer–Weber growth mode. Strain effects repel Ge adatoms from the C-rich domains, leading to enhanced Ge island formation on the C-free surface regions in between the c(4×4) areas. At a low growth temperature of 350°C, very small three-dimensional islands (3–5 nm in diameter, height 3–4 ML) with a density of nearly 1×1012 cm−2 are obtained for only 0.5 ML of Ge. At higher substrate temperatures of approximately 500°C this three-dimensional growth mode is less pronounced, but still evident. The initially nucleated three-dimensional islands define the positions of the larger quantum dots at higher Ge coverage, that exhibit enhanced photoluminescence (PL) properties.  相似文献   

19.
    
Halide perovskite quantum dots (Pe‐QDs) have been considered as outstanding candidates for photodetector, light‐emitting diode, and lasing applications, but these perspectives are being impeded by the severe stability, including both chemical and optical degradations. This study reports on amino‐mediated anchoring Pe‐QDs onto the surfaces of monodisperse silica to effectively depress the optical degradation of their photoluminescence (PL) and random lasing stabilities, hence achieving highly stable and low‐threshold lasing. An amination‐mediated nucleation and growth process is designed for the general and one‐pot synthesis of Pe‐QDs on the surfaces of silica spheres. The facile synthetic process, which can be finished within several minutes, insures scalable production. Surprisingly, almost no PL degradation is observed after 40 d storage under ambient conditions, even 80% PL intensity can be maintained after persistently illuminated by UV lamps for 108 h. Subsequently, extremely stable random lasing is achieved after storage for 2 months or over continuously optical pumping for 8 h. Such high PL and lasing stabilities originate from the isolation effects due to the effective anchoring, which separate the Pe‐QDs from each other and inhibit the photoinduced regrowth and deterioration. This work will also open the window of perovskite‐based multifunctional systems.  相似文献   

20.
    
The poor stability and aggregation problem of CsPbBr3 quantum dots (QDs) in air are great challenges for their future practical application. Herein, a simple and effective ligand‐modification strategy is proposed by introducing 2‐hexyldecanoic acid (DA) with two short branched chains to replace oleic acid (OA) with long chains during the synthesis process. These two short branched chains not only maintain their colloidal stability but also contribute to efficient radiative recombination. The calculations show that CsPbBr3 QDs with DA modification (CsPbBr3‐DA QDs) have larger binding energy than CsPbBr3 QDs with OA (CsPbBr3‐OA QDs), resulting in significantly enhanced stability. Due to the strong binding energy between DA ligands and QDs, CsPbBr3‐DA QDs exhibit no aggregation phenomenon even after stored in air for more than 70 d, and CsPbBr3‐DA QDs films can maintain 94.3% of initial PL intensity after 28 d, while in CsPbBr3‐OA QDs films occurs a rapid degradation of PL intensity. Besides, the enhanced amplified spontaneous emission (ASE) performance of CsPbBr3‐DA QDs films has been demonstrated under both one‐ and two‐photon laser excitation. The ASE threshold of CsPbBr3‐DA QDs films is reduced by more than 50% and their ASE photostability is also improved, in comparison to CsPbBr3‐OA QDs films.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号