Abstract
Surface passivation of perovskite solar cells (PSCs) using a low‐cost industrial organic pigment quinacridone (QA) is presented. The procedure involves solution processing a soluble ...derivative of QA,
N
,
N
‐bis(tert‐butyloxycarbonyl)‐quinacridone (TBOC‐QA), followed by thermal annealing to convert TBOC‐QA into insoluble QA. With halide perovskite thin films coated by QA, PSCs based on methylammonium lead iodide (MAPbI
3
) showed significantly improved performance with remarkable stability. A PCE of 21.1 % was achieved, which is much higher than 18.9 % recorded for the unmodified devices. The QA coating with exceptional insolubility and hydrophobicity also led to greatly enhanced contact angle from 35.6° for the pristine MAPbI
3
thin films to 77.2° for QA coated MAPbI
3
thin films. The stability of QA passivated MAPbI
3
perovskite thin films and PSCs were significantly enhanced, retaining about 90 % of the initial efficiencies after more than 1000 hours storage under ambient conditions.
Abstract
Perovskite light‐emitting diodes (PeLEDs) have received great attention for their potential as next‐generation display technology. While remarkable progress has been achieved in green, red, ...and near‐infrared PeLEDs with external quantum efficiencies (EQEs) exceeding 20%, obtaining high performance blue PeLEDs remains a challenge. Poor charge balance due to large charge injection barriers in blue PeLEDs has been identified as one of the major roadblocks to achieve high efficiency. Here band edge control of perovskite emitting layers for blue PeLEDs with enhanced charge balance and device performance is reported. By using organic spacer cations with different dipole moments, that is, phenethyl ammonium (PEA), methoxy phenethyl ammonium (MePEA), and 4‐fluoro phenethyl ammonium (4FPEA), the band edges of quasi‐2D perovskites are tuned without affecting their band gaps. Detailed characterization and computational studies have confirmed the effect of dipole moment modification to be mostly electrostatic, resulting in changes in the ionization energies of ≈0.45 eV for MePEA and ≈ −0.65 eV for 4FPEA based thin films relative to PEA‐based thin films. With improved charge balance, blue PeLEDs based on MePEA quasi‐2D perovskites show twofold increase of the EQE as compared to the control PEA based devices.
Metal halide perovskite nanocrystals (NCs) have emerged as new-generation light-emitting materials with narrow emissions and high photoluminescence quantum efficiencies (PLQEs). Various types of ...perovskite NCs, e.g., platelets, wires, and cubes, have been discovered to exhibit tunable emissions across the whole visible spectrum. Despite remarkable advances in the field of perovskite NCs, many nanostructures in inorganic NCs have not yet been realized in metal halide perovskites, and producing highly efficient blue-emitting perovskite NCs remains challenging and of great interest. Here, we report the discovery of highly efficient blue-emitting cesium lead bromide (CsPbBr
) perovskite hollow NCs. By facile solution processing of CsPbBr
precursor solution containing ethylenediammonium bromide and sodium bromide, in situ formation of hollow CsPbBr
NCs with controlled particle and pore sizes is realized. Synthetic control of hollow nanostructures with quantum confinement effect results in color tuning of CsPbBr
NCs from green to blue, with high PLQEs of up to 81%.
Perovskite light‐emitting diodes (LEDs) have emerged as new‐generation electroluminescent devices. By using quasi‐2D perovskite/PEO composite thin films as the light‐emitting layer, in article number ...1707093, Biwu Ma and co‐workers report highly efficient spectrally stable red perovskite LEDs with a state‐of‐the‐art maximum brightness of around 1400 cd m−2 and a peak external quantum efficiency exceeding 6.2%.
Mechanochemical synthesis has emerged as a facile method for the preparation of a wide range of organic, inorganic, and polymeric materials. Here, we report the use of mechanochemical synthesis for ...the preparation of ionically bonded organic metal halide hybrids with a zero‐dimensional (0D) structure at the molecular level. (Ph4P)2SbCl5 and (Ph4P)2MnCl4 were synthesized by grinding appropriate ratios of organic halide salt Ph4PCl with inorganic metal halide salts SbCl3 and MnCl2, respectively. The structural and photophysical properties of mechanochemically synthesized (Ph4P)2SbCl5 and (Ph4P)2MnCl4 were characterized, which are almost identical to those of single crystals prepared by slow solution growth. By reacting Ph4PCl with both SbCl3 and MnCl2, we have been able to produce a mixture of two 0D organic metal halide hybrids that exhibit a dual emission covering a wide range of the spectrum with Commission Internationale de l'Eclairage (CIE) coordinates of (0.4898, 0.4800). Our work has clearly established mechanochemical synthesis as an effective method to produce ionically bonded organic‐inorganic hybrids.
Mechanochemical synthesis is applied for the preparation of zero‐dimensional organic metal halide hybrids (Ph4P)2SbCl5 and (Ph4P)2MnCl4. Their structural and photophysical properties were found to be almost identical to those of single crystals prepared via solution growth. A mixture of two 0D hybrids could be mechanochemically synthesized to exhibit dual emission.
Low dimensional metal halide perovskites and hybrids Zhou, Chenkun; Lin, Haoran; He, Qingquan ...
Materials science & engineering. R, Reports : a review journal,
12/2018, Letnik:
137, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Organic-inorganic metal halide hybrids are an important class of crystalline materials with exceptional structural and property tunability. Recently metal halide perovskites with ABX3 structure have ...been extensively investigated as new generation semiconductors for various optoelectronic devices, including photovoltaic cells, light emitting diodes, photodetectors, and lasers, for their exceptional optical and electronic properties. By controlling the morphological dimensionality, low dimensional metal halide perovskites, including 2D perovskite nanoplatelets, 1D perovskite nanowires, and 0D perovskite quantum dots, have been developed to exhibit distinct properties from their bulk counterparts, due to quantum size effects. Besides ABX3 perovskites, organic-inorganic metal halide hybrids, containing the same fundamental building block of metal halide octahedra (BX6), can also be assembled to possess other types of crystallographic structures. Using appropriate organic and inorganic components, low dimensional organic-inorganic metal halide hybrids with 2D, quasi-2D, corrugated-2D, 1D, and 0D structures at the molecular level have been developed and studied. Due to the strong quantum confinement and site isolation, these low dimensional metal halide hybrids at the molecular level exhibit remarkable and unique properties that are significantly different from those of ABX3 perovskites. In light of the rapid development of low dimensional metal halide perovskites and hybrids, it is indeed timely to review the recent progress in these areas. Also, there is a need to clarify the difference between morphological low dimensional metal halide perovskites and molecular level low dimensional metal halide hybrids, as currently the terminologies of low dimensional perovskites are not appropriately used in many cases. Finally, in this review article, we discuss the synthesis, characterization, application, and computational studies of low dimensional metal halide perovskites and hybrids.
Metal Halide Perovskite Light‐Emitting Diodes
Can metal halide perovskite light‐emitting diodes (PeLEDs) become one of the next‐generation LED technologies for display and lighting applications? In ...article number 2000072, Biwu Ma and co‐workers introduce the major progress achieved in the development of efficient and stable PeLEDs to date, discuss the main issues and challenges in the field, and provide their prospects on addressing these issues and challenges.
The rich chemistry of organic metal halide hybrids has enabled the development of a variety of new functional materials with crystal structures beyond perovskites. In article number 1801474, Biwu Ma ...and co‐workers report a novel bulk assembly of one‐dimensional (1D) organic metal halide hybrid, C5H16N2Pb2Br6, in which lead bromide octahedrons form a corrugated chain structure via non‐planar edge‐sharing. This 1D material exhibits a broadband yellow emission peaked at 554 nm with a full width at half maximum of 155 nm with a photoluminescence quantum efficiency of around 10%, due to exciton self‐trapping.
Here, the family of molecular level low–dimensional organic metal halide hybrids has expanded significantly over the last few years. Here a new type of 1D metal halide structure is reported, in which ...metal halide octahedra form a corrugated double–chain structure via nonplanar edge–sharing. This material with a chemical formula of C5H16N2Pb2Br6 exhibits a broadband yellow emission under ultraviolet light excitation with a photoluminescence quantum efficiency of around 10%. The light–yellow emission is considered to be attributed to self–trapping excitons. Theoretical calculations show that the unique alignment of the octahedra leads to small band dispersion and large exciton binding energy. Together with previously reported 1D metal halide wires and tubes, this new bulk assembly of 1D metal halides suggests the potential to develop a library of bulk assemblies of metal halides with controlled structures and compositions.
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