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Showing papers on "Iodide published in 2022"


Journal ArticleDOI
29 Jul 2022-Science
TL;DR: Zhao et al. as discussed by the authors converted PbI2 into an inactive (PbI 2 )2RbCl compound by RbCl doping, which effectively stabilizes the perovskite phase.
Abstract: In halide perovskite solar cells the formation of secondary-phase excess lead iodide (PbI2) has some positive effects on power conversion efficiency (PCE) but can be detrimental to device stability and lead to large hysteresis effects in voltage sweeps. We converted PbI2 into an inactive (PbI2)2RbCl compound by RbCl doping, which effectively stabilizes the perovskite phase. We obtained a certified PCE of 25.6% for FAPbI3 (FA, formamidinium) perovskite solar cells on the basis of this strategy. Devices retained 96% of their original PCE values after 1000 hours of shelf storage and 80% after 500 hours of thermal stability testing at 85°C. Description Managing excess lead iodide In hybrid perovskite solar cells, the formation of lead iodide (PbI2) can provide some passivation effects but can lead to device instability and hysteresis in current–density changes with voltage. Zhao et al. show that doping with rubidium chloride (RbCl) can create a passive inactive (PbI2)2RbCl phase that stabilizes the perovskite phase and lowers its bandgap. Devices exhibited 25.6% certified power efficiency and maintained 80% of that efficiency after 500 hours of operation at 85°C. —PDS Converting PbI2 into inactive (PbI2)2RbCl by RbCl doping can stabilize the perovskite phase and increase efficiency.

294 citations


Journal ArticleDOI
14 Jan 2022-Science
TL;DR: Mixed-valence dilanthanide complexes (CpiPr5)2Ln2I3 (Ln is Gd, Tb, or Dy; CPIPr5, pentaisopropylcyclopentadienyl), which feature a singly occupied lanthanide-lanthanide σ-bonding orbital of 5dz2 parentage, are reported, as determined by structural, spectroscopic, and computational analyses.
Abstract: Description Magnetic effects of lanthanide bonding Lanthanide coordination compounds have attracted attention for their persistent magnetic properties near liquid nitrogen temperature, well above alternative molecular magnets. Gould et al. report that introducing metal-metal bonding can enhance coercivity. Reduction of iodide-bridged terbium or dysprosium dimers resulted in a single electron bond between the metals, which enforced alignment of the other valence electrons. The resultant coercive fields exceeded 14 tesla below 50 and 60 kelvin for the terbium and dysprosium compounds, respectively. —JSY A single electron bond between lanthanide centers induces alignment effects that impart extremely high magnetic coercivity. Metal-metal bonding interactions can engender outstanding magnetic properties in bulk materials and molecules, and examples abound for the transition metals. Extending this paradigm to the lanthanides, herein we report mixed-valence dilanthanide complexes (CpiPr5)2Ln2I3 (Ln is Gd, Tb, or Dy; CpiPr5, pentaisopropylcyclopentadienyl), which feature a singly occupied lanthanide-lanthanide σ-bonding orbital of 5dz2 parentage, as determined by structural, spectroscopic, and computational analyses. Valence delocalization, wherein the d electron is equally shared by the two lanthanide centers, imparts strong parallel alignment of the σ-bonding and f electrons on both lanthanides according to Hund’s rules. The combination of a well-isolated high-spin ground state and large magnetic anisotropy in (CpiPr5)2Dy2I3 gives rise to an enormous coercive magnetic field with a lower bound of 14 tesla at temperatures as high as 60 kelvin.

161 citations


Journal ArticleDOI
TL;DR: In this article , the thermal stability of low-dimensional perovskites based on three hydrophobic organic ammonium salts and their passivation effect toward CsPbI3 and the whole device performance were investigated.
Abstract: Low-dimensional (LD) perovskites can effectively passivate and stabilize 3D perovskites for high-performance perovskite solar cells (PSCs). Regards CsPbI3-based PSCs, the influence of high-temperature annealing on the LD perovskite passivation effect has to be taken into account due to fact the black-phase CsPbI3 crystallization requires high-temperature treatment, however, which has been rarely concerned so far. Here, the thermal stability of LD perovskites based on three hydrophobic organic ammonium salts and their passivation effect toward CsPbI3 and the whole device performance, have been investigated. It is found that, phenyltrimethylammonium iodide (PTAI) and its corresponding LD perovskites exhibit excellent thermal stability. Further investigation reveals that PTAI-based LD perovskites are mainly distributed at grain boundaries, which not only enhances the phase stability of CsPbI3 but also effectively suppresses non-radiative recombination. As a consequence, the champion PSC device based on CsPbI3 exhibits a record efficiency of 21.0 % with high stability.

77 citations


Journal ArticleDOI
01 Mar 2022-Joule
TL;DR: In this paper , a chemical engineering approach based on adding Dipropylammonium iodide (DipI) together with a well-known reducing agent, sodium borohydride (NaBH4), aimed at preventing the premature degradation of tin-based halide perovskites was reported.

59 citations


Journal ArticleDOI
TL;DR: In this article , 2D/3D perovskite films were modulated with 2PbI4 and 1Naphthalenemethylammonium iodide (NpMAI) to reduce the grain boundary defects, improve the charge carrier lifetime and hinders ionic diffusion.
Abstract: Reducing the electronic defects in perovskite films has become a substantial challenge to further boost the photovoltaic performance of perovskite solar cells. Here, 2D (NpMA)2PbI4 perovskite and 1‐naphthalenemethylammonium iodide (NpMAI) are separately introduced into the PbI2 precursor solutions to regulate the crystal growth in a 2D/3D perovskite film using a two‐step deposition method. The (NpMA)2PbI4 modulated perovskite film shows a significantly improved film quality with enlarged grain size from ≈500 nm to over 1000 nm, which greatly reduces the grain‐boundary defects, improves the charge carrier lifetime, and hinders ionic diffusion. As a result, the best‐performing device shows a high power conversion efficiency (PCE) of 24.37% for a small‐area (0.10 cm−2) device and a superior PCE of 22.26% for a large‐area (1.01 cm−2) device. Importantly, the unencapsulated device shows a dramatically improved operational stability with maintains over 98% of its initial efficiency after 1500 h by maximum power point (MPP) tracking under continuous light irradiation.

57 citations


Journal ArticleDOI
TL;DR: In this article , a tribromide ion was used to suppress the iodide interstitial formation and thus reduce charge recombination in bladed WBG perovskite films of Cs0.1FA0.2MA0.7Pb(I0.85Br0.15)3.
Abstract: Wide-bandgap (WBG) mixed-halide perovskites show promise of realizing efficient tandem solar cells but at present suffer from large open-circuit voltage loss and the mechanism is still unclear. Here we show that WBG perovskites with iodide–bromide compositions have an increased concentration of deep traps induced by iodide interstitials, which limits performance of WBG perovskite cells. We employ tribromide ions to suppress the iodide interstitial formation and thus reduce charge recombination in bladed WBG perovskite films of Cs0.1FA0.2MA0.7Pb(I0.85Br0.15)3. The 1-µm-thick opaque WBG perovskite solar cells have an efficiency of 21.9%, a small open-circuit voltage deficit of 0.40 V and a large fill factor of 83%. The efficiency of the best-performing monolithic perovskite–silicon tandem cell using this perovskite reaches 28.6%. The tribromide addition also suppresses light-induced phase segregation in WBG perovskites and thus enhance device stability. Encapsulated tandem cells maintain 93% of their initial efficiency after operation for 550 h. Efficient perovskite–silicon tandem solar cells with an efficiency of up to 28.6% are reported by employing tribromide ions to reduce charge recombination.

53 citations


Journal ArticleDOI
TL;DR: In this paper, a 3D/2D heterostructure layer based on 4-Fluoro-Phenethylammonium iodide (4FPEAI) was successfully fabricated to improve the humidity resistance and the power conversion efficiency of the 3D PSCs.

52 citations


Journal ArticleDOI
TL;DR: In this article , the acquired kapok leaves extract (KLE) and synergistic iodide ions are firstly used as novel environmental-friendly corrosion inhibitors for Q235 carbon steel in 0.5 mol/L H2SO4 solution.

49 citations


Journal ArticleDOI
TL;DR: In this paper , a 3D/2D heterostructure layer based on 4-Fluoro-Phenethylammonium iodide (4FPEAI) was successfully fabricated to improve the humidity resistance and the power conversion efficiency of the 3D PSCs.

45 citations


Journal ArticleDOI
TL;DR: In this article , a bifunctional passivator, methyl haloacetate (methyl chloroacetate, (MClA), methyl bromoacetates (MBrA)), is designed to reduce defect density, to tune the energy levels and to improve interfacial charge extraction in the FAMAPbI3 perovskite cell by synergistic passivation of both C�O groups and halogen anions.
Abstract: Formamidinium methylammonium lead iodide (FAMAPbI3) perovskite has been intensively investigated as a potential photovoltaic material because it has higher phase stability than its pure FAPbI3 perovskite counterpart. However, its power conversion efficiency (PCE) is significantly inferior due to its high density of surface detects and mismatched energy level with electrodes. Herein, a bifunctional passivator, methyl haloacetate (methyl chloroacetate, (MClA), methyl bromoacetate (MBrA)), is designed to reduce defect density, to tune the energy levels and to improve interfacial charge extraction in the FAMAPbI3 perovskite cell by synergistic passivation of both CO groups and halogen anions. As predicted by modeling undercoordinated Pb2+, the MBrA shows a very strong interaction with Pb2+ by forming a dimer complex ([C6H10Br2O4Pb]2+), which effectively reduces the defect density of the perovskite and suppresses non‐radiative recombination. Meanwhile, the Br− in MBrA passivates iodine‐deficient defects. Consequently, the MBrA‐modified device presents an excellent PCE of 24.29%, an open‐circuit voltage (Voc) of 1.18 V (Voc loss ≈ 0.38 V), which is one of the highest PCEs among all FAMAPbI3‐based perovskite solar cells reported to date. Furthermore, the MBrA‐modified devices without any encapsulation exhibit remarkable long‐term stability with only 9% of PCE loss after exposure to ambient air for 1440 h.

32 citations


Journal ArticleDOI
TL;DR: In this article , the metal oxide-based materials for volatile radioactive iodine capture, with limitations on operating conditions, adsorption capacities, and long-term immobilization are discussed.

Journal ArticleDOI
09 Sep 2022-Science
TL;DR: Wang et al. as mentioned in this paper proposed a solution to stabilize hole transport in organic layers by ionic coupling positive polymer radicals and molecular anions through an ion-exchange process, which enabled fabrication of perovskite solar cells with a certified power conversion efficiency of 23.9% that maintained 92% under standard illumination at 85°C after 1000 hours.
Abstract: Highly efficient halide perovskite solar cells generally rely on lithium-doped organic hole transporting layers that are thermally and chemically unstable, in part because of migration of iodide anions from the perovskite layer. We report a solution strategy to stabilize the hole transport in organic layers by ionic coupling positive polymer radicals and molecular anions through an ion-exchange process. The target layer exhibited a hole conductivity that was 80 times higher than that of the conventional lithium-doped layer. Moreover, after extreme iodide invasion caused by light-soaking at 85°C for 200 hours, the target layer maintained high hole conductivity and well-matched band alignment. This ion-exchange strategy enabled fabrication of perovskite solar cells with a certified power conversion efficiency of 23.9% that maintained 92% under standard illumination at 85°C after 1000 hours. Description Avoiding lithium to fight iodide Although lithium-doped organic hole transport layers (HTLs) enable efficient charge extraction in perovskite solar cells, they also promote degradation, because lithium ions can adsorb water and positive radicals that form promote migration of iodide anions from the perovskite layer. Wang et al. developed an organic HTL that coupled positive polymer radicals and molecular anions through an ion-exchange process. The resulting highly conductive HTL has improved energy-level alignment with the perovskite compared with commonly used lithium-doped HTLs. High thermal and chemically stability with respect to iodide migration resulted in stable perovskite solar cells that maintained 92% power conversion efficiency of 23.9% for 1000 hours at 85°C. —PDS Lithium-free hole-transporting layers that couple positive polymer radicals and molecular anions inhibit iodide migration.

Journal ArticleDOI
TL;DR: In this paper , the reduction of per-and polyfluoroalkyl substance (PFAS) decay, defluorination, and transformation product formation in UV/sulfite system (UV/S) + iodide system was investigated.
Abstract: The addition of iodide (I–) in the UV/sulfite system (UV/S) significantly accelerated the reductive degradation of perfluorosulfonates (PFSAs, CnF2n+1SO3–) and perfluorocarboxylates (PFCAs, CnF2n+1COO–). Using the highly recalcitrant perfluorobutane sulfonate (C4F9SO3–) as a probe, we optimized the UV/sulfite + iodide system (UV/S + I) to degrade n = 1–7 PFCAs and n = 4, 6, 8 PFSAs. In general, the kinetics of per- and polyfluoroalkyl substance (PFAS) decay, defluorination, and transformation product formations in UV/S + I were up to three times faster than those in UV/S. Both systems achieve a similar maximum defluorination. The enhanced reaction rates and optimized photoreactor settings lowered the EE/O for PFCA degradation below 1.5 kW h m–3. The relatively high quantum yield of eaq– from I– made the availability of hydrated electrons (eaq–) in UV/S + I and UV/I two times greater than that in UV/S. Meanwhile, the rapid scavenging of reactive iodine species by SO32– made the lifetime of eaq– in UV/S + I eight times longer than that in UV/I. The addition of I– also substantially enhanced SO32– utilization in treating concentrated PFAS. The optimized UV/S + I system achieved >99.7% removal of most PFSAs and PFCAs and >90% overall defluorination in a synthetic solution of concentrated PFAS mixtures and NaCl. We extended the discussion over molecular transformation mechanisms, development of PFAS degradation technologies, and the fate of iodine species.

Journal ArticleDOI
TL;DR: In this paper , an in situ fabrication strategy for a flexible and large-area Tl-doped Cs3Cu2I5 NC-polymer composite scintillation film with a high light yield (∼48800 photons/MeV) and improved stability was developed.
Abstract: Cs3Cu2I5 nanocrystals (NCs) are considered to be promising materials due to their high photoluminescence efficiency and X-ray hardness. However, the present strategy depends on tedious fabrication with excessive chemical waste. The evasive iodide ion dissociation, inadaptable ligand system, low stability, and relatively low light yield severely impede their applications. Herein, we develop an in situ fabrication strategy for a flexible and large-area Tl-doped Cs3Cu2I5 NC-polymer composite scintillation film with a high light yield (∼48800 photons/MeV) and improved stability. Tween 80 and phosphinic acid successfully inhibit the oxidation of iodide ions, and the films can be stored for at least six months. As a result, a high spatial resolution of 16.3 lp mm-1 and a low detection limit of 305 nGyair s-1 were achieved. A radioluminescence intensity of >80% was maintained after a total irradiation dose of 604.8 Gy. These results indicate the promising application of these copper halide NCs in low-cost, flexible, and high-performance medical imaging.

Journal ArticleDOI
TL;DR: In this article , the authors demonstrated that defect passivation effect can be eliminated by incorporation of multifunctional poly(ionic liquid)s (PILs) additives, resulting in ultrastable perovskite solar cells (PVSCs).
Abstract: Longevity is a key constraint for hybrid perovskite based photovoltaics. Here it is demonstrated that ion migration‐induced degradation can be eliminated by incorporation of multifunctional poly(ionic‐liquid)s (PILs) additives, resulting in ultrastable perovskite solar cells (PVSCs). The presence of PILs suffices to construct an “ionic polymer network,” providing the functionalities of defect passivation and ion immobilization by concurrently forming a physical barrier and chemical bonding. Compared with the defect passivation effect for the imidazolium‐based PIL (PIL‐Im) case, the quaternary ammonium‐based PIL (PIL‐Am) shows a higher interaction energy with the perovskite due to the stronger electronic coupling ascribed to the additional complexation, which endows the corresponding perovskite with higher migration energy for iodide ions. As a result, the power conversion efficiency (PCE) of anion‐cation‐mixed hybrid n‐i‐p PVSCs with PIL‐Am is remarkably improved from 20.26% to 22.22%. Specifically, the PILs‐modified device perfectly retains its dark current characteristics upon a cooling (−40 °C)–heating (85 °C) process. The unencapsulated PIL‐Am stabilized PVSC maintains 80% of the initial PCE under AM 1.5G light soaking for nearly 1500 h. The corresponding device also displays pronounced stability under thermal stress or realistic operation conditions.

Journal ArticleDOI
TL;DR: In this article , the successive incorporation of tetrabutylammonium (TBA) into MAPbI3 perovskite has been reported to increase the crystallinity, grain size, surface morphology without pin-hole, and roughness of the thin films.
Abstract: This work reported the successive incorporation of tetrabutylammonium (TBA) into Methylammonium lead Iodide (MAPbI3) perovskite. The thin films were characterized by X-Ray diffraction (XRD), Scanning electron microscopy (SEM), Transmittance electron microscopy (TEM), Atomic force microscopy (AFM), and UV-Visible spectroscopy. It was shown that introducing TBA increases the crystallinity, grain size, surface morphology without pin-hole, and roughness of the MAPbI3 thin films. Moreover, the MA(1-X)TBAX PbI3 thin film shows better stability in a relative humidity of ∼60% after 15 days than the pure MAPbI3 thin film. The obtained results are hoped to be helpful for stability and improvement of the performance of the MAPbI3 thin films by doping TBA cations under ambient conditions.

Journal ArticleDOI
TL;DR: In this article, the authors proposed a potential pathway to realize stable energy storage in aqueous zinc-halogen batteries by applying the synergistic regulation of electrode and electrolyte to confine the charged products.

Journal ArticleDOI
TL;DR: In this article , a 2D iodide double perovskite photoferroelectric is reported based on Ag/Sb ions, which possesses a high Curie temperature of 414 K (above BaTiO3), large spontaneous polarization of 9.6 μC cm−2, ferroelectric photovoltaic effect, and photostrictive effect.
Abstract: 2D hybrid halide double perovskites (HHDPs) have been demonstrated to be a promising alternative to conventional lead‐based halide perovskites as a new system of photoferroelectrics, due to their unique characteristics of environmental friendliness, favorable stability, and fascinating optoelectronic properties. Herein, for the first time, a 2D iodide double perovskite photoferroelectric is reported based on Ag/Sb ions, (4,4‐DFPD)4AgSbI8 (4,4‐DFPD = 4,4‐difluoropiperidinium), which possesses a high Curie temperature of 414 K (above BaTiO3), a large spontaneous polarization of 9.6 μC cm−2, ferroelectric photovoltaic effect, and photostrictive effect. Notably, to the best of the authors’ knowledge, the discovery of photostriction in HHDP photoferroelectrics is unprecedented. Moreover, (4,4‐DFPD)4AgSbI8 exhibits an impressive X‐ray responsivity, with a sensitivity as high as 704.8 μC Gyair−1 cm−2 at 100 V bias and a detection limit as low as 0.36 μGyair s−1 at 10 V bias, both of which outperform the current all HHDP photoferroelectrics. This work enriches the photoferroelectric family, and proves that Ag/Sb‐based HHDP photoferroelectrics are a promising candidate for the next‐generation optoelectronic devices.

Journal ArticleDOI
TL;DR: In this article , a triple-layer mesoporous architecture was proposed to stabilize pure α-FAPbI3, which is an ideal material for single-junction cells.
Abstract: Perovskite materials have been particularly eye-catching by virtue of their excellent properties such as high light absorption coefficient, long carrier lifetime, low exciton binding energy and ambipolar transmission (perovskites have the characteristics of transporting both electrons and holes). Limited by the wider band gap (1.55 eV), worse thermal stability and more defect states, the first widely used methylammonium lead iodide has been gradually replaced by formamidinium lead iodide (FAPbI3) with a narrower band gap of 1.48 eV and better thermal stability. However, FAPbI3 is stabilized as the yellow non-perovskite active phase at low temperatures, and the required black phase (α-FAPbI3) can only be obtained at high temperatures. In this perspective, we summarize the current efforts to stabilize α-FAPbI3, and propose that pure α-FAPbI3 is an ideal material for single-junction cells, and a triple-layer mesoporous architecture could help to stabilize pure α-FAPbI3. Furthermore, reducing the band gap and using tandem solar cells may ulteriorly approach the Shockley-Queisser limit efficiency. We also make a prospect that the enhancement of industrial applications as well as the lifetime of devices may help achieve commercialization of PSCs in the future.

Journal ArticleDOI
01 Sep 2022-Joule
TL;DR: In this article , Cs and dimethylammonium cations were incorporated simultaneously into the A-site of perovskite structure to increase the band gap while maintaining the tolerance factor.

Journal ArticleDOI
01 Jun 2022
TL;DR: In this article , a new NaF sacrificing layer is introduced between the perovskite layer and ETL, which is sacrificed during cell fabrication by penetrating into the polysilicon layer, improving the pervskite film quality, while partial NaF is incorporated into the mesoporous TiO2 ETL during NaF layer fabrication to passivate TiO 2 and construct a well matched energy level alignment.
Abstract: As next-generation photovoltaic devices, methylammonium lead iodide (MAPbI3)-based organic-inorganic halide perovskite solar cells (PSCs) have received considerable attention because of their cost effectiveness and high efficiency. However, their practical applications are retarded due to severe instability under moisture, thermal and sunlight conditions, which are closely related to the insufficient perovskite film quality and high photocatalytic activity of defective TiO2 electron-transporting layer (ETL) to accelerate the perovskite decomposition. Herein, remarkably enhanced power conversion efficiency (PCE) and stability of MAPbI3-based PSCs is reached through the use of a new sodium fluoride (NaF) sacrificing layer, which, introduced between the perovskite layer and ETL, is sacrificed during cell fabrication by penetrating into the perovskite layer, improving the perovskite film quality, while partial NaF is incorporated into the mesoporous TiO2 ETL during NaF layer fabrication to passivate TiO2 and construct a well-matched energy level alignment. As a result, the optimized PSC generates a high PCE of 20.9%, which is 17% higher than that of the pristine cell (17.9%), and outstanding performance stability due to remarkably enhanced moisture, thermal and sunlight stability. This study highlights a simple and effective approach to boost the PCE and durability of MAPbI3-based PSCs simultaneously, accelerating the commercialization of this technology.

Journal ArticleDOI
TL;DR: In this article , a mini review of the application of polypyridyl-based copper complexes in dye-sensitized solar cells (DSSCs) is briefly discussed in this mini review.

Journal ArticleDOI
TL;DR: In this article, two-dimensional perovskites (FxPEA)2PbI4 (x = 1, 2, 3, 5) were grown in situ on the surface of the three-dimensional (3D) perovskiy and demonstrate effective passivation of the surface defects of 3D perovskyy.

Journal ArticleDOI
TL;DR: In this article , the authors proposed a potential pathway to realize stable energy storage in aqueous zinc-halogen batteries by applying the synergistic regulation of electrode and electrolyte to confine the charged products.

Journal ArticleDOI
TL;DR: In this paper, hydrazine chloride (HACl) was used to promote favorable grain orientation during the growth of perovskite crystals, leading to a power conversion efficiency of 22.32% (certified PCE of 21.59%).

Journal ArticleDOI
12 Sep 2022
TL;DR: In this paper , a dual-network structured hydrogel electrolyte composed of polyacrylamide (PAM), sodium alginate (SA) and potassium iodide (KI) was developed for solid-state zinc-air/iodide hybrid batteries.
Abstract: As a key component of batteries, the electrolyte determines the ion transport and interface chemistry of the cathode and anode. In this work, we develop a dual-network structured hydrogel electrolyte composed of polyacrylamide (PAM), sodium alginate (SA) and potassium iodide (KI) for solid-state zinc-air/iodide hybrid batteries. The assembled hybrid battery shows excellent renewability and a long cycling life of 110 h with a high energy efficiency of 80%. The ion-crosslinked dual-network structure endows the material with improved mechanical strength and increased ionic conductivity. More importantly, the introduction of iodine species not only offers more favorable cathodic kinetics of iodide/iodate redox than oxygen electrocatalysis but also regulates the solvation structure of zinc ions to ensure better interface stability. This work provides significant concepts for developing novel solid-state electrolytes to realize high-performance energy devices and technologies.

Journal ArticleDOI
TL;DR: In this paper , the use of coordination complexes of the more abundant first row d-block metals, in particular copper, iron and zinc, as dyes in DSCs is discussed.
Abstract: The use of renewable energy is essential for the future of the Earth, and solar photons are the ultimate source of energy to satisfy the ever-increasing global energy demands. Photoconversion using dye-sensitized solar cells (DSCs) is becoming an established technology to contribute to the sustainable energy market, and among state-of-the art DSCs are those which rely on ruthenium(ii) sensitizers and the triiodide/iodide (I3−/I−) redox mediator. Ruthenium is a critical raw material, and in this review, we focus on the use of coordination complexes of the more abundant first row d-block metals, in particular copper, iron and zinc, as dyes in DSCs. A major challenge in these DSCs is an enhancement of their photoconversion efficiencies (PCEs) which currently lag significantly behind those containing ruthenium-based dyes. The redox mediator in a DSC is responsible for regenerating the ground state of the dye. Although the I3−/I− couple has become an established redox shuttle, it has disadvantages: its redox potential limits the values of the open-circuit voltage (VOC) in the DSC and its use creates a corrosive chemical environment within the DSC which impacts upon the long-term stability of the cells. First row d-block metal coordination compounds, especially those containing cobalt, and copper, have come to the fore in the development of alternative redox mediators and we detail the progress in this field over the last decade, with particular attention to Cu2+/Cu+ redox mediators which, when coupled with appropriate dyes, have achieved VOC values in excess of 1000 mV. We also draw attention to aspects of the recyclability of DSCs.

Journal ArticleDOI
TL;DR: In this paper , two-dimensional perovskites (FxPEA)2PbI4 (x = 1, 2, 3, 5) are grown in situ on the surface of the three-dimensional (3D) perovsite and demonstrate effective passivation of the surface defects.

Journal ArticleDOI
TL;DR: In this paper , a multi-amine chelating ligand, N′-(2-aminoethyl)-N′-hexadecylethane-1,2-diamine (AHDA), was used to stabilize the intrinsically dynamic surface of metal halide perovskite nanocrystals.
Abstract: Developing pathways to stabilize the intrinsically dynamic surface of metal halide perovskite nanocrystals (PNCs), especially metastable lead iodide PNCs, is an important but challenging task. Herein, we have realized ultra-stable colloidal CsPbI3 PNCs based on a multi-amine chelating ligand, N′-(2-aminoethyl)-N′-hexadecylethane-1,2-diamine (AHDA). The protonated AHDA can anchor the PNC surface lattice with a high binding energy of 2.36 eV, much larger than the 1.47 eV achieved with the commonly used oleylammonium ligands. The chelation effect greatly inhibits dynamic desorption of surface ligands and enables stabilization of CsPbI3 PNCs under various ambient stimuli, such as repeated purification (up to 15 cycles), polar solvents, heat, and light. The stable yet easily accessible surface of the AHDA-capped CsPbI3 PNCs renders them a robust photocatalyst in a stereoselective C–C oxidative coupling reaction. Furthermore, we show that the AHDA ligand can also be used to synthesize PNCs of several other compositions, namely CsPbCl3, CsPbBr3, CsPbBrI2, and hybrid FAPbI3 (FA = formamidine), with remarkably stable emission characteristics.

Journal ArticleDOI
TL;DR: In this article , a compatible facial post-treatment of CsPbII3 nanocrystals using guanidinium iodide (GuI) was reported.
Abstract: The remarkable evolution of metal halide perovskites in the past decade makes them promise for next-generation optoelectronic material. In particular, nanocrystals (NCs) of inorganic perovskites have demonstrated excellent performance for light-emitting and display applications. However, the presence of surface defects on the NCs negatively impacts their performance in devices. Herein, we report a compatible facial post-treatment of CsPbI3 nanocrystals using guanidinium iodide (GuI). It is found that the GuI treatment effectively passivated the halide vacancy defects on the surface of the NCs while offering effective surface protection and exciton confinement thanks to the beneficial contribution of iodide and guanidinium cation. As a consequence, the film of treated CsPbI3 nanocrystals exhibited significantly enhanced luminescence and charge transport properties, leading to high-performance light-emitting diode with maximum external quantum efficiency of 13.8% with high brightness (peak luminance of 7039 cd m-2 and a peak current density of 10.8 cd A-1). The EQE is over threefold higher than performance of untreated device (EQE: 3.8%). The operational half-lifetime of the treated devices also was significantly improved with T50 of 20 min (at current density of 25 mA cm-2), outperforming the untreated devices (T50 ~ 6 min).