Abstract: The present disclosure provides a method for facet-selective passivation on each crystal facet of colloidal nanocrystals via solution-phase ligand exchange process, thereby providing highly-passivated and colloidally-stable nanocrystal inks. This ligand exchange strategy separately addresses polar and non-polar facets precluding from deleterious nanocrystal aggregation in the colloid. The method involves the introduction of alkali metal organic complexes during metal halide conventional solution exchanges, and one specific example is Na+·Ac?. Alkali metal ions stabilize and passivate non polar facets whereas polar facets are passivated through metal halides. This strategy leads to a significant decrease in nanocrystal aggregation during and after ligand exchange, and to improved photophysical properties stemming from this. The resulting nanocrystal solid films exhibit improved stability, retain their absorption features, and have a minimized Stokes shift.

Abstract: Ge-centered octahedral perovskites have heretofore not been achievable due to collapse of the perovskite structure into non-octahedral units due to a lack of B site support from the small-radius Ge atom, which breaks Goldschmidt’s rules for constructing octahedral perovskites. To overcome this shortcoming, a strategy was developed to form a strong cage with the A sites in which the octahedron is forced to remain intact. Strong intermolecular interaction between the organic A site cations were used to stabilize the symmetric Ge octahedral perovskite beyond the Goldschmidt’s rules. The molecules used based on Y-PMA (Y: F, Cl, Br, I) that facilitated strong halogen bonding to form the cage around the octahedral. Octahedral Ge perovskites exhibit a direct bandgap in contrast to the indirect bandgap of non-octahedral Ge perovskites are demonstrated. In addition, the octahedral Ge perovskite exhibited a dramatic increase in the carrier mobility.

Abstract: A semiconductor nanocrystal particle including a transition metal chalcogenide represented by Chemical Formula 1, the semiconductor nanocrystal particle having a size of less than or equal to about 100 nanometers, and a method of producing the same: M1M2Cha3??Chemical Formula 1 wherein M1 is Ca, Sr, Ba, or a combination thereof, M2 is Ti, Zr, Hf, or a combination thereof, and Cha is S, Se, Te, or a combination thereof.

Abstract: Methods are disclosed to restore the halide ions lost in the purification (ligand removal) of photoluminescent cesium lead halide or FA lead halide perovskite quantum dots. Quantum dots thus prepared can be used to deposit solid films with high packing density featuring dots with <0.4 nm gaps therebetween, low trap density 1/40 of previously reported, high mobility 100× previously reported, high photoluminescent quantum yield exceeding 90%, high external quantum yield exceeding 20%, and increased stability under electrical current. The quantum dots are used to formulate inks suitable for ink jet printing, drop casting, spin coating, and other solution-based methods for forming emissive layers used in light producing semiconductor devices.

Abstract: A semiconductor nanocrystal particle represented by Chemical Formula 1 and having a full width at half maximum (FWHM) of less than or equal to about 30 nanometers (nm) in the emission wavelength spectrum is provided: AxA?(3+??x)D(2+?)E(9+?). ??Chemical Formula 1 In Chemical Formula 1, A is a first metal including Rb, Cs, or a combination thereof, A? is an organic substance derived from an ammonium salt, an organic material derived from an organic ligand, or an organic material including a combination thereof, D is a second metal including Sb, Bi, or a combination thereof E is Cl, Br, I, or a combination thereof, 1<x?3, ?1<?<1, 3+??x>0, ?1<?<1, and ?1<?<1.

Abstract: Methods are disclosed to restore the halide ions lost in the purification (ligand removal) of photoluminescent cesium lead halide or FA lead halide perovskite quantum dots. Quantum dots thus prepared can be used to deposit solid films with high packing density featuring dots with <0.4 nm gaps therebetween, low trap density 1/40 of previously reported, high mobility 100× previously reported, high photoluminescent quantum yield exceeding 90%, high external quantum yield exceeding 20%, and increased stability under electrical current. The quantum dots are used to formulate inks suitable for ink jet printing, drop casting, spin coating, and other solution-based methods for forming emissive layers used in light producing semiconductor devices.

Abstract: A semiconductor nanocrystal particle represented by Chemical Formula 1 and having a full width at half maximum (FWHM) of less than or equal to about 30 nanometers (nm) in the emission wavelength spectrum is provided: AxA?(3+??x)D(2+?)E(9+?).??Chemical Formula 1 In Chemical Formula 1, A is a first metal including Rb, Cs, or a combination thereof, A? is an organic substance derived from an ammonium salt, an organic material derived from an organic ligand, or an organic material including a combination thereof, D is a second metal including Sb, Bi, or a combination thereof E is Cl, Br, I, or a combination thereof, 1<x?3, ?1<?<1, 3+??x>0, ?1<?<1, and ?1<?<1.

Abstract: Disclosed herein are perovskite based optoelectronic devices made entirely via solution-processing at low temperatures (<150° C.) which provide for simple manufacturing, compatibility with flexible substrates, and perovskite-based tandem devices. These perovskite based optoelectronic devices are produced using an electron transport layer on which the perovskite layer is formed which is passivated using a ligand selected to reduce electron-hole recombination at the interface between the electron transport layer and the perovskite layer.

Abstract: Disclosed herein are lattice-anchored materials that combine cesium lead halide perovskites with lead chalcogenide colloidal quantum dots (CQDs) that surprisingly exhibit stability exceeding that of the constituent materials. The CQDs keep the perovskite in its desired cubic phase, suppressing the transition to the undesired, lattice-mismatched, phases. These composite materials exhibit an order of magnitude enhancement in air stability for the perovskite, showing greater than six months' stability in room ambient as well as being stable for more than five hours at 200° C. in air. The perovskite prevents oxidation of the CQD surfaces and reduces the nanoparticles' agglomeration under 100° C. by a factor of five compared to CQD controls. The matrix-protected CQDs exhibit 30% photoluminescence quantum efficiency for a CQD solid emitting at infrared wavelengths.

Abstract: The present invention relates to highly polarizable 3D organic perovskites of the general formula ABX3, prepared by introducing halogen functional groups in the A-site cation (in which the A and B sites are occupied by organic cations and the X site is a monovalent non-metallic counterion). The (DCl)(NH4)(BF4)3 crystal exhibits a strong linear electrooptic (EO) effect with an effective EO coefficient of 20 pmV?1, which is 10 times higher than that of metal halide perovskites. These 3D organic perovskites are solution processed and compatible with silicon, and illustrate the potential of rationally-designed all-organic perovskites for use in on-chip modulators, electro-optic devices, piezoelectric devices, or silicon photonics devices.

Abstract: Novel 2D organic-inorganic hybrid perovskites, including (4-CF3-PMA)2PbI4, that emit in the blue spectral region, and methods for making same. The CF3-substituted material exhibits a ˜0.16 eV larger bandgap than corresponding halogen-substituted materials. This family of materials offers a degree of freedom in tuning 2D perovskites to specific bandgaps for optoelectronic applications. These materials are highly stable, easily synthesized, and do not suffer from phase separation.

Abstract: Disclosed is a quantum dot based solar cell device which includes a substrate, a light harvesting structure sandwiched between electrically conducing layers, with at least one electrically conducting layer being substantially transparent with the light harvesting structure being located on the substrate. The light harvesting structure includes a layer of semiconducting quantum dots, with this layer of semiconducting quantum dots including at least two distinct sets of semiconducting quantum dots which are homogenously mixed. One of the two distinct sets of semiconducting quantum dots has a first bandgap and the at least one other distinct set of semiconducting quantum dots has a second bandgap different from the first bandgap. Both sets of semiconducting quantum dots are passivated with any one or combination of halides and pseudo-halides.

Abstract: The present disclosure provides substantially homogeneously dispersed multimetal oxy-hydroxide catalyst comprising at least two metals, at least one metal being a transition metal, and at least a second metal which is structurally dissimilar to at least one metal, such that the multimetal oxy-hydroxide is characterized by being substantially homogeneously dispersed and generally not crystalline. A key feature of the present materials is that the presence of the structurally dissimilar metal results in sufficient strain produced in the final multimetal oxy-hydroxide material to prevent crystallization from occurring. The resulting materials are specifically not annealed at temperatures that would induce crystallization in order to avoid the expected phase segregation that would occur during crystallization.

Abstract: A class of crystals comprises an inorganic lattice in which organic molecules are embedded, thereby allowing macroscopic electro-optic responsiveness. The lattice is based on a metal halide perovskite structure. The organic molecules can be with an intrinsic dipole such that when aligned and fixed in place in the inorganic lattice, they induce electro-optic responsiveness in the macroscopic crystal. Alternatively, their mere presence in the structure can induce sufficient polarity in the scaffold itself for a similar responsiveness. The molecules themselves can comprise a carbon backbone that is completely conductive, partially conductive, or non-conductive, as well as zero, one or two functional groups that allow binding to the lattice and increased polarity.

Abstract: Disclosed herein are homogeneous CQD bulk homojunction solids prepared through a cascade surface modification (CSM) strategy. The CSM includes an initial halogenation step of CQD surfaces to attain an initial sufficient passivation; and a subsequent step that reprograms CQD surfaces with functional ligands to control the doping character and solubility properties of the resulting CQD inks. The resulting p-type and n-type CQDs exhibit a distinct potential difference, which induces a built-in electric field between the constituent classes of CQDs. By controlling the colloidal solubility of the inks, homogeneous CQD bulk homojunction films have been achieved, whereas it is shown that the use of prior ink strategies results in inhomogeneous films as a result of poor miscibility. The homogeneous CQD bulk homojunction films exhibit a 1.5-fold increase in the carrier diffusion length and outperforms previously-reported CQD solar cells, achieving a record PCE of 13.3%.

Abstract: The present disclosure provides a method for facet-selective passivation on each crystal facet of colloidal nanocrystals via solution-phase ligand exchange process, thereby providing highly-passivated and colloidally-stable nanocrystal inks. This ligand exchange strategy separately addresses polar and non-polar facets precluding from deleterious nanocrystal aggregation in the colloid. The method involves the introduction of alkali metal organic complexes during metal halide conventional solution exchanges, and one specific example is Na+.Ac?. Alkali metal ions stabilize and passivate non polar facets whereas polar facets are passivated through metal halides. This strategy leads to a significant decrease in nanocrystal aggregation during and after ligand exchange, and to improved photophysical properties stemming from this. The resulting nanocrystal solid films exhibit improved stability, retain their absorption features, and have a minimized Stokes shift.

Abstract: Optoelectronic devices, such as photovoltaic device and light-emitting diode, are provided. The devices include a quasi two-dimensional layered perovskite material and a passivating agent chemically bonded to the quasi two-dimensional layered perovskite material. The passivating agent includes a phosphine oxide compound. An active material is also provided. The active material includes a quasi two-dimensional perovskite compound having outermost edge(s), and a passivating agent chemically bonded to the outermost edge(s). The passivating agent includes a phosphine oxide compound. Methods for manufacturing the optoelectronics devices and the active material are also provided.

Abstract: A semiconductor nanocrystal particle represented by Chemical Formula 1 and having a full width at half maximum (FWHM) of less than or equal to about 30 nanometers (nm) in the emission wavelength spectrum is provided: AxA?(3+??x)D(2+?)E(9+?). ??Chemical Formula 1 In Chemical Formula 1, A is a first metal including Rb, Cs, or a combination thereof, A? is an organic substance derived from an ammonium salt, an organic material derived from an organic ligand, or an organic material including a combination thereof, D is a second metal including Sb, Bi, or a combination thereof E is Cl, Br, I, or a combination thereof, 1<x?3, ?1<?<1, 3+??x>0, ?1<?<1, and ?1<?<1.

Abstract: An optoelectronic device has an electron transport layer, an active layer, and a hole transport layer. Each of the electron transport layer, the active layer, and the hole transport layer has quantum dots.

Abstract: A PIN type infrared photodiode including a first electrode, a n-type semiconductor, an atomic layer deposition coating of lead sulfide, a p-type semiconductor and a second electrode, wherein the n-type semiconductor comprises nanowires conformally coated with the atomic layer deposition coating of lead sulfide.