Micromachines
·
2019
·Vol. 10
·期 7
·459
·
IF 2.426
Yuanming Zhou,Sijiong Mei,Dongwei Sun,Neng Liu,Wuxing Shi,Jiahuan Feng,Fei Mei,Jinxia Xu,Yan Jiang,Xianan Cao
High efficiency perovskite light-emitting diodes (PeLEDs) using PEDOT:PSS/MoO3-ammonia composite hole transport layers (HTLs) with different MoO3-ammonia ratios were prepared and characterized. For PeLEDs with one-step spin-coated CH3NH3PbBr3emitter, an optimal MoO3-ammonia volume ratio (0.02) in PEDOT:PSS/MoO3-ammonia composite HTL presented a maximum luminance of 1082 cd/m2and maximum current efficiency of 0.7 cd/A, which are 82% and 94% higher than those of the control device using pure PEDOT:PSS HTL respectively. It can be explained by that the optimized amount of MoO3-ammonia in the composite HTLs cannot only facilitate hole injection into CH3NH3PbBr3through reducing the contact barrier, but also suppress the exciton quenching at the HTL/CH3NH3PbBr3interface. Three-step spin coating method was further used to obtain uniform and dense CH3NH3PbBr3films, which lead to a maximum luminance of 5044 cd/m2and maximum current efficiency of 3.12 cd/A, showing enhancement of 750% and 767% compared with the control device respectively. The significantly improved efficiency of PeLEDs using three-step spin-coated CH3NH3PbBr3film and an optimum PEDOT:PSS/MoO3-ammonia composite HTL can be explained by the enhanced carrier recombination through better hole injection and film morphology optimization, as well as the reduced exciton quenching at HTL/CH3NH3PbBr3interface. These results present a promising strategy for the device engineering of high efficiency PeLEDs.
研究领域:
材料科学
·
光电工程
✓ 已验证
DOI
高影响因子
Nanoscale
·
2018
·Vol. 10
·期 24
·11452-11459
·
IF 7.233
Lijia Liu,Jitao Li,John A. McLeod
We report a series of Eu-substituted methylammonium lead tribromide quantum dots (MAPb1−xEuxBr3 QDs). The crystallinity of these QDs increases with increasing Eu content, while there is only a small change in the lattice constant, and the morphology of the MAPb1−xEuxBr3 QDs is unaffected by the Eu content. This demonstrates that Eu is a suitable element for substituting Pb while retaining the original crystal structure. We observe blue photoluminescence (PL) consistent with Eu2+, which, at high Eu content (x = 0.3), contributes luminescence intensity equal to the green PL of unsubstituted MAPbBr3 QDs. As Eu is a less toxic substitute for Pb, that also provides blue luminescence, MAPb1−xEuxBr3 QDs may prove to be a valuable optoelectronic material.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
Advanced Photonics Research
·
2021
·Vol. 3
·期 1
·2100198
·
IF 0
Lu Cao,Jie Wang,Jia-Rui Rao,Guang-Zhe Ma,Min Gao,Dong Shi
Metal halide perovskites (MHPs) are attracting ever-growing interest across diverse optoelectronic subdisciplines. Yet, the physical mechanism underlying photoexcitation and subsequent photocarrier dynamics remains poorly understood, due to the apparent spectroscopic diversities observed for any certain MHP. Here, diverse spectroscopic characteristics, including static spectral line-shapes and time-resolved photoluminescence (TRPL) traces shown by polycrystalline versus single-crystalline CH 3 NH 3 PbBr 3 perovskites, are restudied. Key photophysical merits, including exciton binding energy ( E B ), Sommerfeld factor ( ξ ), and Urbach energy ( E U ) that account for the diversities, are discussed within the established framework of semiconductor optics. The value of ξ , which increases with E B , determines how much the interband absorption is enhanced beyond that expected for free carriers. The intrinsic band-edge luminescence is identified, with its asymmetric spectral line-shape linked to E U via the van Roosbroeck–Shockley relation. Excited phase evolution, accompanied by rapid electron–hole (e–h) pairs dissociation and subsequent occurrence of e–h plasma, is indicated by the two-stage TRPL traces that are only observable for high-quality single crystals. With all the spectroscopic analysis and interpretations rooted in the established semiconductor optical theorems, the mechanistic merits revealed in this study are informative for plausible identification between the interband and excitonic photophysical processes of MHPs.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
ACTA PHYSICO-CHIMICA SINICA
·
2017
·Vol. 33
·期 10
·2099-2105
·
IF 0.767
WANG Ya-Nan,MA Pin,PENG Lu-Mei,ZHANG Di,FANG Yan-Yan,ZHOU Xiao-Wen,LIN Yuan
Lead acetate, which is highly soluble in dimethylformamide, was used to synthesize mixed halide perovskite CH3NH3PbBr3-xClx(MA = CH3NH3, 0≤x≤3) nanocrystals (NCs). This method provides an approach to address the
low solubility of lead halides, especially lead chloride. Different Br/Cl ratios in MAPbBr3-xClx lead to various optical properties. The photoluminescence emission peak can be tuned from 399 to 527 nm. Their full-widths at half-maxima (FWHM) are about 20 nm. MAPbBr3-xClxNCs
have an average diameter of ~(11 ± 3) nm and have uniform dispersion in toluene. The MAPbBr3 NCs have a long average recombination lifetime (Tave = 97.4 ns) and a photoluminescence quantum yield (PLQY) of up to 73%.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2021
·
IF 4.126
Qianrui Lv,Chong Li,Lijing Zhang
Developing strategies to modify lead-based metal halide perovskite lattice has become an increasingly important effort because of the need to control fundamental material properties. In this paper, we introduced a flow microreactor for the continuous synthesis of Mn-substituted methylammonium lead tribromide (CH3NH3Pb1–xMnxBr3) quantum dots. The original crystal structure can be retained at high Mn content (x = 0.3). The size and photoluminescence peak of the CH3NH3Pb1–xMnxBr3 quantum dots can be tuned by varying the molar ratio of Pb/Mn. With increasing Mn content, the photoluminescence peak shifted gradually to shorter wavelengths. Mn-substitution also affects the air stability for the quantum dots. CH3NH3Pb0.7Mn0.3Br3 shows the best air stability, and polystyrene can be used to protect the quantum dots. Compared to CH3NH3PbBr3 quantum dots, CH3NH3Pb1–xMnxBr3 quantum dots may prove to be a less toxic and valuable optoelectronic material meeting the requirements for different practical applications.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
FARADAY DISCUSSIONS
·
2016
·Vol. 196
·91-99
·
IF 3.544
Feng Zhang,Tianye Zhou,Guogang Liu,Jianbing Shi,Haizheng Zhong,Yuping Dong
The surfaces of semiconductor nanocrystals have been known to be a very important factor in determining their optical properties. The introduction of functionalized ligands can further enhance the interactions between nanocrystals, which is beneficial for the assembly of nanocrystals. In a previous report, we developed a ligand-assisted reprecipitation method to fabricate organometal halide perovskite nanocrystals capped with octylamine and oleic acid. Here, a TPE derivative 3-(4-(1,2,2-triphenylvinyl)phenoxy)propan-1-amine, which shows a typical aggregation induced emission feature, is applied to replace octylamine to fabricate CH3NH3PbBr3 nanocrystals. The obtained CH3NH3PbBr3 nanocrystals were nanocubes (average diameter ∼ 11.1 nm) and are likely to assemble into ordered superstructures. By adjusting the chain length of the TPE derivative, we found that the assembly of the CH3NH3PbBr3 nanocrystals was correlated with the interactions between the TPE groups. This provides a new platform to investigate the ligand effects in nanocrystal solids and may potentially achieve enhanced optical and electrical properties.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2022
·
IF 4.171
Yu-Qi Sun,Jie Wang,Guang-Zhe Ma,Dong Shi
Photoluminescence is informative to other optoelectronic processes that are less directly accessible in metal halide perovskites . In this study, we conducted optical studies on CH 3 NH 3 PbBr 3 single crystals with robust cubic lattices and atomically flat surfaces. Inter-band luminescence peaking aside from the absorption cutoff was observed, and its shifts toward shorter wavelength upon cooling. Cooling the crystal below 150 K leads to the occurrence of mid-gap luminescence partly at the expense of the inter-band luminescence, which indicates bulk photoluminescence quenching by trap-mediated electronic trapping and subsequent mid-gap radiation following electronic de-trapping. Time-resolved photoluminescence probed at the mid-gap luminescence maxima shows two-stage mono-exponential traces, directly corroborating the trapping and de-trapping processes. In the presence of mid-gap luminescence at low temperatures, time-resolved inter-band luminescence demonstrates triplet decaying pathways, in sharp contrast to the doublet decaying pathways at higher temperatures in the absence of mid-gap luminescence. Time- and temperature-resolved inter-band photoluminescence gave rise to a characteristic photocarrier lifetimes evolution against temperature in a close analogy to the material's dielectric constant .
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
ChemNanoMat
·
2017
·Vol. 3
·期 5
·303-310
·
IF 2.937
Feng Zhang,Cheng Chen,Stephen V. Kershaw,Changtao Xiao,Junbo Han,Bingsuo Zou,Xing Wu,Shuai Chang,Yuping Dong,Andrey L. Rogach,Haizheng Zhong
Light-emitting halide perovskites are currently emerging as promising solution-processed materials for optoelectronic applications, and correlations between their physical properties and morphologies are important drivers to guide material and device optimization. There is still a lack of precise control of the morphology in colloidal perovskite materials, and in the related studies of their shape-dependent optical properties. Capitalizing on our previous works on the ligand-assisted reprecipitation synthesis of colloidal perovskite nanocrystals, we have addressed the role of key experimental parameters in determining the degree of supersaturation that drives the crystallization of CH 3 NH 3 PbBr 3 precursors. By adjusting the amount of ligands, we fabricated single crystalline CH 3 NH 3 PbBr 3 nanocubes (size: ≈500 nm) and nanowires (length: 2–4.5 μm, width: ≈100 nm), and conducted steady-state, time-resolved, excitation power and temperature-dependent photoluminescence measurements to investigate their shape-dependent photoluminescence properties.
研究领域:
材料科学
·
纳米技术
·
光电子学
·
光物理
·
钙钛矿半导体
✓ 已验证
DOI
高影响因子
Journal of Physical Chemistry C
·
2019
·
IF 4.309
Weizheng Wang,Yumeng Zhang,Wenhui Wu,Xiaoyu Liu,Xuanxuan Ma,Guixiang Qian,Jiyang Fan
The organic–inorganic hybrid metal halide perovskites with different dimensions and diverse architectures are highly attractive materials for optoelectronic applications. However, people know little about the dynamics of their formation processes. Here, we study both experimentally and theoretically the self-assembly formation dynamics of the luminescent colloidal CH3NH3PbBr3 nanocrystals. We have observed their successive transformations from original spherical quantum dots to periodically stacked nanoplatelets when the primitive colloidal nanocrystals with a high concentration were maintained in liquid for a prolonged period of time. A theoretical dynamic collision model by taking into account the popular van der Waals force, the polarization force that is unique for the perovskites, and the electrostatic forces between particle surfaces in the presence of the surface ligands is proposed to explain the self-assembly process of the colloidal CH3NH3PbBr3 nanocrystals. The result reveals that the rather easy self-assembly of the organic–inorganic hybrid perovskites with different morphologies in the absence of enough surface ligands is closely related to their intrinsic polarization force, whereas the presence of the surface ligands could hamper the self-assembly process. The proposed theoretical model is general and can be used to analyze the self-assembly dynamics of various types of colloidal nanostructures.
研究领域:
材料科学
·
光学
·
化学动力学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2016
·Vol. 4
·期 41
·9651-9655
·
IF 5.066
Wei Xu,Feiming Li,Zhixiong Cai,Yiru Wang,Feng Luo,Xi Chen
An organic–inorganic hybrid fluorescent perovskite, CH3NH3PbBr3, was synthesized by a grinding method, and applied for humidity sensing. Its strong fluorescence at 530 nm could be linearly quenched by a humidity increase from 7 to 98%. Coupled with a red-emitting reference dye, 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin, a colorimetric humidity sensor was produced using the perovskite. The sensor appeared to be sensitive to increased humidity by displaying a color change from green to red, or vice versa, with good reversibility. The proposed approach should provide a new strategy in the design of sensitive and applicable humidity sensors.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2018
·
IF 3.779
Yun Tang,Nan Yan,Zhiwei Wang,Hudie Yuan,Yalou Xin,Hongfeng Yin
Ligand-assisted reprecipitation (LARP) technique is a powerful approach for the synthesis of organometal halide perovskite nanocrystals (PNCs). The morphology and surface property of the formed PNCs which determine their optical properties are ultrasensitive to the synthetic parameters. To guarantee the batch-to-batch reproducibility of PNCs with excellent optical properties, it is of central importance to better understand the factors influencing the formation of PNCs during LARP process. Herein the dual-factor of the amount of perovskite precursor and the polarity of mixture solvent was modified by varying precursor solution volume (PSV) in the LARP system. The concentration, size, surface state and optical properties of the synthesized CH 3 NH 3 PbBr 3 PNCs as a function of PSV were systematically investigated aiming to understand the influence of the dual-factor on the nucleation and growth of PNCs. Experimental results revealed that few crystal nuclei was generated due to lower amount of precursor at lower PSV, which was favorable for the growth of large perovskite crystals. At the higher PSV, the inhibition of crystal growth with increased amount of precursor was compensated by increasing the polarity of mixture solvent, which led to the dissolution of surface ligands and eventually growth of large perovskite crystals. The obtained results on PSV-dependent synthesis of PNCs will be used as a guide to optimize the synthetic parameters in the LARP process.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2019
·
IF 3.683
Nan Yan,Hongfeng Yin,Zhiwei Wang,Hudie Yuan,Yalou Xin,Yun Tang
Amines, ammonium salts, and their combination with organic acids are commonly employed ligands during the synthesis of colloidal perovskite nanocrystals (PNCs). However, the role of surface coordination, derived from different ammonium derivative ligands, on the optical properties of PNCs remains poorly understood. In this study, octylamine (OA), octylammonium bromide (OABr), and oleic acid (OAc) were applied, standing for amine, ammonium salt, and organic acid, respectively. The effects of four different types of ligands, including OA, OABr, OA-OAc, and OABr-OAc, on the surface coordination and subsequently optical properties of CH3NH3PbBr3 PNCs were comparatively investigated. Compared to amine ligand, the ammonium salt could coordinate to both surface cations and anions of PNCs to passivate their surface defects more effectively, leading to enhanced optical properties including higher photoluminescence (PL) spectral intensities and PL quantum yield. Moreover, the combination of OAc with amine rather than ammonium salt ligand could trigger the protonation–deprotonation reaction to further improve their coordination effect on a PNC’s surface, thus leading to significantly enhanced optical properties of PNCs. This study clarified the surface coordination of different ammonium derivative ligands and their role on the optical properties of PNCs, which could guide the design of ligands during the synthesis of PNCs.
研究领域:
材料科学
·
纳米技术
·
光电子学
·
胶体化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）