Search Results (34)

Formamidinium lead bromide (FAPbBr₃) quantum dots (QDs) have shown potential in light-emitting diodes (LEDs). However, their performance is constrained by surface defects and the limitations of charge transport. Zwitterionic ligands, owing to their twin functions of Lewis base coordination and electrostatic compensation, passivate surface defects of perovskite QDs. Some other zwitterionic ligands are high-cost, while amino acids, as zwitterionic ligands, are inexpensive, readily available, and have efficient passivation capabilities. Their short main chain and programmable side chain can control the volume and dipole at Å-scale range through functional group selection and feed ratio regulation, achieving interface energy level engineering. This work adopts green-emitting FAPbBr₃ QDs as the model, tuning ligand properties by modifying side-chain functional groups, thereby achieving PLQY of 87.2%. Experimental results and DFT reveal that amino acids preferentially undergo coordination and can be further fine-tuned through conjugated contacts. Without severe site competition and without affecting coordination occupation and ligand uniformity, the EQE reaches 5.6% and the luminance exceeds 9000 cd/m². This low-cost technology is easily scalable and broadly manufacturable, providing a replicable material and interface design route for green zone perovskite LEDs. Full article

In this study, we investigate the influence of the halogen elements bromine (Br) and chlorine (Cl) on iodine defect properties primarily in FAPbI₃ through first-principles calculations, aiming to understand the effect of high defect densities on the efficiency of organic–inorganic hybrid perovskite cells. The results indicate that Br and Cl interstitials minimally alter the overall band structure of FAPbI₃ but significantly modify the defect energy levels. Br and Cl interstitials, with defect states closer to the valence band and lower formation energies, effectively convert deep-level traps induced by iodine interstitials (I_i) into shallow-level traps. This conversion enhances carrier transport by reducing non-radiative recombination while preserving light absorption efficiency. Excess Br/Cl co-doping in FAPbI₃ synthesis thereby suppresses non-radiative recombination and mitigates the detrimental effects of iodide-related defects. Full article

Despite the huge progress achieved in the optimization of perovskite solar cell (PSC) performance, stability remains a limiting factor for technological commercialization. Here, a study on the photovoltaic, structural and morphological stability of semi-transparent formamidinium lead bromide-based PSCs is presented. This work focuses on the positive role of 2D nanoscale layer passivation, induced by perovskite surface treatment with a mixture of iso-Pentylammonium chloride (ISO) and neo-Pentylammonium chloride (NEO). In situ X-ray diffraction (XRD) is applied in combination with atomic force microscopy (AFM), and the results are correlated to the devices’ photovoltaic performances. The superior power conversion efficiency and overall stability of the ISO-NEO system is evidenced, as compared to the un-passivated device, under illumination in air. Furthermore, the role of the ISO-NEO treatments in increasing the morpho-structural stability is clarified as follows: a bulk effect resulting in a protective role against the loss in crystallinity of the perovskite 3D phase (observed only for the un-passivated device) and an interface effect, being the observed 2D phase crystallinity loss spatially localized at the interface with the 3D phase where a higher concentration of defects is expected. Importantly, the complete stability of the device is achieved with the passivated ISO-NEO-encapsulated device, allowing us to exclude the intrinsic degradation effects. Full article

To produce highly efficient and repeatable perovskite solar cells (PSCs), comprehending interfacial loss and developing approaches to ameliorate interfacial features is essential. Nonradiative recombination at the SnO₂–perovskite interface in SnO₂-based perovskite solar cells (PSCs) leads to significant potential loss and variability in device performance. To improve the quality of the SnO₂ electron transport layer, a novel polymer-doped SnO₂ matrix, specifically using polyacrylic acid, was developed. This matrix is formed by spin-coating a SnO₂ colloidal solution that includes polymers. The polymer aids in dispersing nanoparticles within the substrate and is evenly distributed in the SnO₂ solution. As a result of the polymer addition, the density and wetting properties of the SnO₂ layer substantially improved. Subsequently, perovskite-based photovoltaic devices comprising SnO₂ and Spiro-OMeTAD layers and using (FAPbI₃)_0.97(MAPbBr₃)_0.03 perovskite are constructed. These optimized devices exhibited an increased efficiency of 17.2% when compared to the 15.7% power conversion efficiency of the control device. The incorporation of polymers in the electron transport layer potentially enables even better performance in planar perovskite solar cells. Full article

The results of numerical SRIM and SCAPS calculations for the ionization, displacement and heating of hybrid perovskites under the influence of protons (E = 0.15, 3.0 and 18 MeV) are presented and show that the lowest transfer energy is demonstrated by the MAPbI₃, FAPbBr₃ and FAPbI₃ compounds, which represent the greatest potential for use as solar cells in space devices. On the other hand, it is found that perovskite compositions containing FA and Cs and with mixed cations are the most stable from the point of view of the formation of vacancies and phonons and are also promising as radiation-resistant materials with respect to powerful proton fluxes. Taking into account the lateral distribution of proton tracks showed that, at an energy level of several MeV, the release of their energy can be considered uniform over the depth and area of the entire solar cell, suggesting that the simple protection by plastic films from the low-energy protons is sufficient. Full article

Reducing the interfacial defects between the perovskite/electron transport layer (ETL) is the key point to improving the efficient and stable performance of perovskite solar cells (PSCs). In this study, two self-assembled molecules ((aminomethyl)phosphonic acid and glycine) with different functional groups (phosphonic acid (-H₂PO₃) and carboxylic acid (-COOH)) were mixed to form the buried bottom interface of PSCs. The synergistic effect of -H₂PO₃ with its higher anchoring ability and -COOH with its fast carrier transport improved the performance of PSCs. Additionally, the SnO₂ modified by mixed self-assembly molecules (M-SAM) showed a more appropriate energy level alignment, favoring charge transport and minimizing energy loss. In addition, the amine group (-NH₂) on the two small molecules effectively interacted with uncoordinated Pb²⁺ in perovskite and improved the quality of the perovskite films. Consequently, the (FAPbI₃)_0.992(MAPbBr₃)_0.008 PSCs with M-SAM reached a PCE of 24.69% (0.08 cm²) and the perovskite modules achieved a champion efficiency of 18.57% (12.25 cm² aperture area). Meanwhile, it still maintained more than 91% of its initial PCE after being placed in nitrogen atmosphere at 25 °C for 1500 h, which is better than that of the single-SAM and control devices. Further reference is provided for the future commercialization of perovskite with efficient and stable characteristics. Full article

Herein, titanium-dioxide-decorated organic formamidinium lead bromide perovskite thin films grown by the one-step spin-coating method are studied. TiO₂ nanoparticles are widespread in FAPbBr₃ thin films, which changes the optical properties of the perovskite thin films effectively. Obvious reductions in the absorption and enhancements in the intensity of the photoluminescence spectra are observed. Over 6 nm, a blueshift of the photoluminescence emission peaks is observed due to 5.0 mg/mL TiO₂ nanoparticle decoration in the thin films, which originates from the variation in the grain sizes of the perovskite thin films. Light intensity redistributions in perovskite thin films are measured by using a home-built confocal microscope, and the multiple scattering and weak localization of light are analyzed based on the scattering center of TiO₂ nanoparticle clusters. Furthermore, random lasing emission with sharp emission peaks is achieved in the scattering perovskite thin films with a full width at the half maximum of 2.1 nm. The multiple scattering of light, the random reflection and reabsorption of light, and the coherent interaction of light within the TiO₂ nanoparticle clusters play important roles in random lasing. This work could be used to improve the efficiency of photoluminescence and random lasing emissions, and it is promising in high-performance optoelectrical devices. Full article

Although perovskite solar cells have achieved excellent photoelectric conversion efficiencies, there are still some shortcomings, such as defects inside and at the interface as well as energy level dislocation, which may lead to non-radiative recombination and reduce stability. Therefore, in this study, a double electron transport layer (ETL) structure of FTO/TiO₂/ZnO/(FAPbI₃)_0.85(MAPbBr₃)_0.15/Spiro-OMeTAD is investigated and compared with single ETL structures of FTO/TiO₂/(FAPbI₃)_0.85(MAPbBr₃)_0.15/Spiro-OMeTAD and FTO/ZnO/(FAPbI₃)_0.85(MAPbBr₃)_0.15/Spiro-OMeTAD using the SCAPS-1D simulation software, with special attention paid to the defect density in the perovskite active layer, defect density at the interface between the ETL and the perovskite active layer, and temperature. Simulation results reveal that the proposed double ETL structure could effectively reduce the energy level dislocation and inhibit the non-radiative recombination. The increases in the defect density in the perovskite active layer, the defect density at the interface between the ETL and the perovskite active layer, and the temperature all facilitate carrier recombination. Compared with the single ETL structure, the double ETL structure has a higher tolerance for defect density and temperature. The simulation outcomes also confirm the possibility of preparing a stable perovskite solar cell. Full article

Formamidinium lead bromide (FAPbBr₃) nanocrystals have emerged as a powerful platform for optoelectronic applications due to their pure green photoluminescence (PL). However, their low colloidal stability under storage and operation reduces the potential use of FAPbBr₃ perovskite nanocrystals (PeNCs) in various applications. In this study, we prepared the poly(L–lactic acid) (PLLA) nanofibrous membrane embedded with FAPbBr₃ perovskite nanocrystals by electrospinning the perovskite and PLLA precursor solution. This is a simple and low-cost technique for the direct confinement of nano-sized functional materials in the continuous polymer nanofibres. PLLA as a polymer matrix provided a high surface framework to fully encapsulate the perovskite NCs. In addition, we found that FAPbBr₃ PeNCs crystallize spontaneously inside the PLLA nanofibre. The resultant PLLA-FAPbBr₃ nanofibrous membranes were stable and remained in the water for about 45 days without any evident decomposition. The results of this research support the idea of new possibilities for the production of air-stable FAPbBr₃ PeNCs by forming a composite with PLLA polymer. The authors believe this study is a new milestone in the development of highly stable metal halide perovskite-based nanofibres, which allow for potential use in lasers, waveguides, and flexible energy harvesters. Full article

All inorganic CsPbBr₃ superstructures (SSs) have attracted much research interest due to their unique photophysical properties, such as their large emission red-shifts and super-radiant burst emissions. These properties are of particular interest in displays, lasers and photodetectors. Currently, the best-performing perovskite optoelectronic devices incorporate organic cations (methylammonium (MA), formamidinium (FA)), however, hybrid organic–inorganic perovskite SSs have not yet been investigated. This work is the first to report on the synthesis and photophysical characterization of APbBr₃ (A = MA, FA, Cs) perovskite SSs using a facile ligand-assisted reprecipitation method. At higher concentrations, the hybrid organic–inorganic MA/FAPbBr₃ nanocrystals self-assemble into SSs and produce red-shifted ultrapure green emissions, meeting the requirement of Rec. 2020 displays. We hope that this work will be seminal in advancing the exploration of perovskite SSs using mixed cation groups to further improve their optoelectronic applications. Full article

Constitutive engineering by adding halide anions is one effective way to improve the performance of photodetectors by adjusting the bandgap. In this study, a mixed-anion perovskite thin film was facile fabricated by post-processing of a pure FAPbI₃ film with a formamidinium bromide (FABr) solution. In addition, the manufactured thin film was used as the light absorption layer, SnO₂-SDBS as the electron transport layer, and spiro-OMeTAD as the hole injection layer to fabricate a deep ultraviolet(UV) photodetector. The device exhibited a response of 43.8 mA/W⁻¹, a detectability of 3.56 × 10¹³ Jones, and an external quantum efficiency of 38%. Therefore, this study is promising for various applications in the deep-UV wavelength region. Full article

Deep-ultraviolet (UV) sensing has attracted significant interest because of its wide range of applications. A mixed-cation halide perovskite-based photodetector prepared by mixing CH₃NH₃PbX₃ (X = I, Br, and Cl) and HC(NH₂)PbX₃ (X = I, Br, and Cl) exhibits high stability and excellent light absorption. In this study, perovskite was prepared by mixing CH₃NH₃⁺ (FA⁺) and HC(NH₂)₂⁺ (MA⁺) cations using I⁻, Br⁻, and Cl⁻ halide anions. The bandgaps of the prepared perovskites increased to 1.48, 2.25, and 2.90 eV with I-, Br-, and Cl-, respectively, and the light absorption spectra shifted to shorter wavelengths. An increase in the redshift of the light absorption led to an increase in the photocurrent. The FAPbCl₃-MAPbCl₃-based photodetector showed a high responsivity of 5.64 mA/W, a detectivity of 4.03 × 10¹¹, and an external quantum efficiency of 27.3%. The results suggested that the FAPbCl₃-MAPbCl₃ perovskite is suitable for deep-UV light sensing and is an excellent candidate for the fabrication of a sensitive photodetector. Full article

Three-dimensional lead halide perovskites are known for their excellent optoelectronic properties, making them suitable for photovoltaic and light-emitting applications. Here, we report for the first time the Raman spectra and photoluminescent (PL) properties of recently discovered three-dimensional aziridinium lead halide perovskites (AZPbX₃, X = Cl, Br, I), as well as assignment of vibrational modes. We also report diffuse reflection data, which revealed an extended absorption of light of AZPbX₃ compared to the MA and FA counterparts and are beneficial for solar cell application. We demonstrated that this behavior is correlated with the size of the organic cation, i.e., the energy band gap of the cubic lead halide perovskites decreases with the increasing size of the organic cation. All compounds show intense PL, which weakens on heating and shifts toward higher energies. This PL is red shifted compared to the FA and MA counterparts. An analysis of the PL data revealed the small exciton binding energy of AZPbX₃ compounds (29–56 meV). Overall, the properties of AZPbX₃ are very similar to those of the well-known MAPbX₃ and FAPbX₃ perovskites, indicating that the aziridinium analogues are also attractive materials for light-emitting and solar cell applications. Full article

In the framework of the dipole approximation, it is shown that in the perovskites quantum dots (QDs) ${\mathrm{FAPbBr}}_{3 }$and {en} ${\mathrm{FAPbBr}}_{3 }$ interacting with low-intensity light, the oscillator strengths of transitions, as well as the dipole moments allowing transitions between one-particle electron quantum-confined states, attain values considerably (by two orders of magnitude) exceeding the typical values of the corresponding quantities in semiconductors. It has been established that the maximum values of the cross-section optical absorption of perovskite QDs are reached at the resonant frequencies of electron transitions. This makes it possible to use such nanosystems as of strong absorption nanomaterials in a wide range of infrared waves. Full article