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Throughout years, the two-step spin-coating process is the most common method to prepare organic lead halide perovskite materials. However, the short reaction time of dropping the solution at the second step means that PbI2 cannot be completely transformed into perovskite phase. To solve this problem, we report the introduction of glycine hydrochloride (GlyHCl) into the second step of the two-step spin-coating process to prepare a FA0.9MA0.1PbI3-x%-GlyHCl perovskite material (namely FAMA-x%-GlyHCl, where FA = formamidinium, MA = methylammonium, and x% stands for the molar ratio of GlyHCl added in FA iodide/MA iodide (FAI/MAI) precursor solution). The Cl− ion in GlyHCl assists the formation of α-phase perovskite, and the −COO− group coordinates with Pb2+ cation in a bridging way, making up for the anion vacancy in perovskite lattice and resulting in high absorption intensity. The perovskite solar cells (PSCs) based on FAMA-9%-GlyHCl achieve a long carrier lifetime (527.0 ns), a photoelectric conversion efficiency (PCE) of 19.40% and good thermal stability, maintaining 85.8% of the initial PCE after being continuously heated at 60 °C for 500 h. This study helps to solve the problem of incomplete reaction in the two-step spin-coating process and puts forward a new solution for preparing high coverage perovskite films with large grain size. [ABSTRACT FROM AUTHOR]

Metal–halide perovskite nanocrystals (NCs) have gained significant attention in the field of optoelectronic and photonic devices due to their promising applications. Despite their exceptional optical properties, the impact of different synthetic strategies on the fundamental nature of NCs, such as nonradiative recombination centers, remains poorly understood. In this study, we investigated the photophysical properties of CsPbBr3 NCs synthesized using two distinct methods, hot injection and ligand-assisted reprecipitation, at the individual particle level. We observed different blinking behaviors under specific photoexcitation power densities and proposed, through intensity–lifetime analysis and Monte–Carlo simulations, that these different synthetic strategies can fabricate NCs with similar crystal structures but distinct surface quenchers with varying energy levels, which significantly affected the photo-induced blinking-down and blinking-up behaviors in individual NCs. Our findings indicate a practical and feasible approach for controlling defect engineering in perovskite NCs, with significant implications for their use in optoelectronic and other technological applications. [ABSTRACT FROM AUTHOR]

All-inorganic perovskites, adopting cesium (Cs+) cation to completely replace the organic component of A-sites of hybrid organic–inorganic halide perovskites, have attracted much attention owing to the excellent thermal stability. However, all-inorganic iodine-based perovskites generally exhibit poor phase stability in ambient conditions. Herein, we propose an efficient strategy to introduce antimony (Sb3+) into the crystalline lattices of CsPbI2Br perovskite, which can effectively regulate the growth of perovskite crystals to obtain a more stable perovskite phase. Due to the much smaller ionic radius and lower electronegativity of trivalent Sb3+ than those of Pb2+, the Sb3+ doping can decrease surface defects and suppress charge recombination, resulting in longer carrier lifetime and negligible hysteresis. As a result, the all-inorganic perovskite solar cells (PSCs) based on 0.25% Sb3+ doped CsPbI2Br light absorber and screen-printable nanocarbon counter electrode achieved a power conversion efficiency of 11.06%, which is 16% higher than that of the control devices without Sb3+ doping. Moreover, the Sb3+ doped all-inorganic PSCs also exhibited greatly improved endurance against heat and moisture. Due to the use of low-cost and easy-to-process nanocarbon counter electrodes, the manufacturing process of the all-inorganic PSCs is very convenient and highly repeatable, and the manufacturing cost can be greatly reduced. This work offers a promising approach to constructing high-stability all-inorganic PSCs by introducing appropriate lattice doping. [ABSTRACT FROM AUTHOR]

Organic-inorganic metal halide perovskites have attained extensive attention owing to their outstanding photovoltaic performances, but the existence of numerous defects in crystalline perovskites is still a serious constraint for the further development of perovskite solar cells (PSCs). In particular, the rapid crystallization guided by anti-solvents leads to plenty of surficial and interfacial defects in perovskite films. Herein, we report the adoption of a pseudo-halide anion based ionic liquid additive, 1-butyl-3-methylimidazolium thiocyanate (BMIMSCN) for growing ternary cation (CsFAMA, where FA = formamidinium and MA = methylammonium) perovskites with large-scale crystal grains and strong preferential orientation via the enhanced Ostwald ripening. Meanwhile, a novel halide-free passivator, benzylammonium formate (BAFa), was employed as a buffering layer on the perovskite films to suppress surface-dominated charge recombination. As a result, the cooperative effects of BMIMSCN additive and BAFa passivator lead to significant enhancements on fluorescence lifetime (from 79.41 to 201.01 ns), open-circuit voltage (from 1.13 to 1.19 V), and photoelectric conversion efficiency (from 18.90% to 22.33%). Moreover, the BMIMSCN/BAFa-CsFAMA PSCs demonstrated greatly improved stability against moisture and heat. This work suggests a promising strategy to improve the quality of perovskite materials via reducing the surficial and interfacial defects by the synergistic effects of lattice doping and interface engineering. [ABSTRACT FROM AUTHOR]

One of the unique characteristics of semiconductors is the strong dependence of their properties on crystal defects and doping. However, due to the species diversity and low density, it is very difficult to control the type and concentration of the defects. In perovskite materials, crystal defects are randomly formed during the fast crystallization process, causing large heterogeneity of the samples. Here, in this work, we report a controllable method to introduce surface defects on CH3NH3PbI3 perovskite materials via the interaction with 1,4-benzoquinone (BQ) molecules on the gas and solid interface. After the adsorption of BQ molecules on the perovskite surface, surface defects can be generated by photoinduced chemical reactions. The concentration of the defects can thus be controlled by precisely regulating the laser irradiation time. The concentration of the defects can be characterized by a gradually decreased PL intensity and lifetime and was found to influence the atmospheric response and the subsequent acetone-induced degradation of the materials. These results demonstrate that crystal defects in perovskite materials can be controllably introduced, which provides a possible way to fully understand the correlation between the nature and chemical structure of these defects. [ABSTRACT FROM AUTHOR]

Inorganic perovskite materials have attracted broad interest in the last several years due to their stability and promising applications as photovoltaic and light‐emitting materials. In this work, we prepared Cs4PbBr6 nanoparticles showing stable photoluminescence (PL) without blinking and studied the PL properties of individual Cs4PbBr6 nanoparticles in the biological temperature range. We found that both PL intensity and lifetime of a single Cs4PbBr6 particle strongly depends on the temperature. The PL intensity and lifetime decrease almost linearly with the increasing of the temperature. The slopes of the PL intensity and lifetime versus temperature were as high as 2% and 3% per degree centigrade, respectively. The photostability and thermal stability were also checked for individual particles. With these results, we proposed that the sensitivity of PL intensity and lifetime of a single Cs4PbBr6 nanoparticle on temperature showed the potential application of a single particle as a nanothermometer for thermal detection in a local environment. Take the temperature: Non‐blinking Cs4PbBr6 nanoparticles show potential as a single‐particle thermometers to detect local temperatures on the nanometer scale. [ABSTRACT FROM AUTHOR]

Organometal halide perovskites have attracted broad interest over the last several years for their promising applications in solar cells and light-emitting devices. It is believed that crystal defects play important roles in the photophysical processes. However, the detailed mechanism is still unclear. In this work, by using luminescence microscopy, we characterized the quenching defects correlating with crystal size, location and morphology. It is clear that needle-shaped crystals own better crystal quality with less defects; and more defects are located in the center of the crystals comparing to the edge. Relatively higher concentration of PbI 2 precursor will generate more defects during the preparation. Characterization of defects is the first step to understand the quenching mechanism and to fully understand the photophysical properties of organometal halide perovskite. [ABSTRACT FROM AUTHOR]

Cesium lead halide perovskite (CsPbX 3) nanocrystals (NCs) have exhibited promising applications in light-emitting diodes (LEDs) due to their tunable bandgap and high quantum efficiency. Backlighting LEDs based on CsPbBr 3 NCs with green emission have been widely designed to show their superiority. However, unlike CsPbBr 3 NCs, backlighting LEDs composed of mixed-halide perovskite (CsPbBr x I 3-x) NCs have rarely been reported and should be further applied in colorful LEDs for granted, mainly because of the unexpected destructive effects from the commercial polymer matrix verified in this work. Purification of a commercial polymer matrix was promoted as an effective method to eliminate the destructive effects. Further investigation proved that the species with strong polarity and oxidability, e.g., BPO in commercial PMMA, are responsible for such destructive effects by inducing the structural transformation of CsPbBr x I 3-x NCs. We believe such results can help to gain a deeper understanding of the degradation mechanism of mixed-halide perovskite materials and indicate a promising method to develop stable colorful perovskite-based LEDs. • Commercial polymer matrix have unexpected destructive effects on CsPbBr x I 3-x NCs. • Destructive effects were from the synergistic effect between polar species in commercial polymer matrix and CsPbBr x I 3-x NCs. • Purification of the commercial polymer matrix can be an effective method to eliminate the destructive effects. • CsPbBr x I 3-x NCs embedded in purified PMMA can exhibit superior stability in both solution and film. [ABSTRACT FROM AUTHOR]

Solution-processed organometal halide perovskites (OMHPs) have been widely used in optoelectronic devices, and have exhibited brilliant performance. One of their generally recognized advantages is their easy fabrication procedure. However, such a procedure also brings uncertainty about the opto-electric properties of the final samples and devices, including morphology, stability, coverage ratio, and defect concentration. Normally, one needs to find a balanced condition, because there is a competitive relation between these parameters. In this work, we fabricated CH3NH3PbI3 films by carefully changing the ratio of the PbI2 to CH3NH3I, and found that the stoichiometric and solvent engineering not only determined the photoluminescence efficiency and defects in the materials, but also affected the photostability, morphology, and coverage ratio. Combining solvent engineering and the substitution of PbI2 by Pb(Ac)2, we obtained an optimized fabrication condition, providing uniform CH3NH3PbI3 films with both high photoluminescence efficiency and high photostability under either I-rich or Pb-rich conditions. These results provide an optimized fabrication procedure for CH3NH3PbI3 and other OMHP films, which is crucial for the performance of perovskite-based solar cells and light emitting devices. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic halide perovskite solar cells (PSCs) have achieved intriguingly high photoelectric conversion efficiencies (PCEs), but their operational stability is still not satisfactory owing to their vulnerability to moisture and heat. Herein, we report the introduction of pseudohalide thiocyanate ions and potassium dopants into formamidinium lead triiodide (FAPbI 3) to obtain a new class of pseudohalide-substituted lead halide perovskites FAPb(SCN) 2 I that can be prepared in ambient air and exhibit broad-range light absorption. Through the introduction of K+-cation doping, hole-conductor-free PSCs based on a FA 0.98 K 0.02 Pb(SCN) 2 I perovskite light absorber and a low-cost, screen-printable carbon-based counter electrode exhibited a PCE of 13.39%. Importantly, the FA 0.98 K 0.02 Pb(SCN) 2 I-based hole-conductor-free PSCs exhibited an 88% PCE retention even after continuous heating at 100 °C for 1020 h, indicating excellent thermal stability. This study suggests that the compositional engineering of non-iodine X-site pseudohalide anion substitution and A-site cation doping hold great promise for improving the stability of PSCs. [ABSTRACT FROM AUTHOR]