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The development of tin-lead alloyed halide perovskite nanocrystals (PNCs) is highly desirable for creating ultrastable, eco-friendly optoelectronic applications. However, the current incorporation of tin into the lead matrix results in severe photoluminescence (PL) quenching. To date, the precise atomic-scale structural origins of this quenching are still unknown, representing a significant barrier to fully realizing the potential of these materials. Here, we uncover the distinctive defect-related microstructures responsible for PL quenching using atomic-resolution scanning transmission electron microscopy and theoretical calculations. Our findings reveal an increase in point defects and Ruddlesden-Popper (RP) planar faults with increasing tin content. Notably, the point defects include a spectrum of vacancies and previously overlooked antisite defects with bromide vacancies and cation antisite defects emerging as the primary contributors to deep-level defects. Furthermore, the RP planar faults exhibit not only the typical rock-salt stacking pattern found in pure Pb-based PNCs but also previously undocumented microstructures rich in bromide vacancies and deep-level cation antisite defects. Direct strain imaging uncovers severe lattice distortion and significant inhomogeneous strain distributions caused by point defect aggregation, potentially breaking the local force balance and driving RP planar fault formation via lattice slippage. Our work illuminates the nature and evolution of defects in tin-lead alloyed halide perovskite nanocrystals and their profound impact on PL quenching, providing insights that support future material strategies in the development of less toxic tin-lead alloyed perovskite nanocrystals.
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Iodine-doped bromide perovskite single crystals (IBPSCs) have important applications in optoelectronic fields, such as in solar cells. Currently, much research has aimed to study the phase separation phenomenon and device performance improvements in IBPSCs. However, important intrinsic photoexcited carrier dynamics are often overlooked in IBPSCs. Here, we explored the photoexcited carrier dynamics in typical iodine-doped MAPbBr3 single crystals using the excitation intensity-dependent steady-state photoluminescence (PL) and time-resolved photoluminescence (TRPL) technique. We found that the trap state density changes with an increase in the amount of doped iodine. Further, we noticed that there is an influence of carrier diffusion on the photoexcited carrier dynamics, and then, we evaluated the carrier diffusion coefficients and recombination constants via numerical simulations of the PL kinetics. Consequently, we found that the electron shallow trap-related carrier behaviors substantially impacted the PL kinetics. Our results greatly facilitate a deeper understanding of the fundamental characteristics of mixed halide perovskite material.
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Nowadays, the extensively used lead sulfide (PbS) quantum dot (QD) hole transport layer (HTL) relies on layer-by-layer method to replace long chain oleic acid (OA) ligands with short 1,2-ethanedithiol (EDT) ligands for preparation. However, the inevitable significant volume shrinkage caused by this traditional method will result in undesired cracks and disordered QD arrangement in the film, along with adverse increased defect density and inhomogeneous energy landscape. To solve the problem, a novel method for EDT passivated PbS QD (PbS-EDT) HTL preparation using small-sized benzoic acid (BA) as intermediate ligands is proposed in this work. BA is substituted for OA ligands in solution followed by ligand exchange with EDT layer by layer. With the new method, smoother PbS-EDT films with more ordered and closer QD packing are gained. It is demonstrated stronger coupling between QDs and reduced defects in the QD HTL owing to the intermediate BA ligand exchange. As a result, the suppressed nonradiative recombination and enhanced carrier mobility are achieved, contributing to ≈20% growth in short circuit current density (Jsc) and a 23.4% higher power conversion efficiency (PCE) of 13.2%. This work provides a general framework for layer-by-layer QD film manufacturing optimization.
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Driven by the intricacy of the illness and the need for individualized treatments, targeted therapy and biomarker research in thyroid cancer represent an important frontier in oncology. The variety of genetic changes associated with thyroid cancer demand more investigation to elucidate molecular details. This research is clinically significant since it can be used to develop customized treatment plans. A more focused approach is provided by targeted therapies, which target certain molecular targets such as mutant BRAF or RET proteins. This strategy minimizes collateral harm to healthy tissues and may also reduce adverse effects. Simultaneously, patient categorization based on molecular profiles is made possible by biomarker exploration, which allows for customized therapy regimens and maximizes therapeutic results. The benefits of targeted therapy and biomarker research go beyond their immediate clinical impact to encompass the whole cancer landscape. Comprehending the genetic underpinnings of thyroid cancer facilitates the creation of novel treatments that specifically target aberrant molecules. This advances the treatment of thyroid cancer and advances precision medicine, paving the way for the treatment of other cancers. Taken simply, more study on thyroid cancer is promising for better patient care. The concepts discovered during this investigation have the potential to completely transform the way that care is provided, bringing in a new era of personalized, precision medicine. This paradigm shift could improve the prognosis and quality of life for individuals with thyroid cancer and act as an inspiration for advances in other cancer types.
Asunto(s)
Calidad de Vida , Neoplasias de la Tiroides , Humanos , Neoplasias de la Tiroides/tratamiento farmacológico , Neoplasias de la Tiroides/genética , Pronóstico , Medicina de Precisión , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismoRESUMEN
Inorganic tin (Sn) perovskite nanocrystals offer a promising solution to the potential toxicity concerns associated with their established lead (Pb)-based counterparts. Yet, achieving their superior stability and optoelectronic properties remains an ongoing challenge. Here, we report a synthesis of high-symmetry α-phase CsSnI3 nanocrystals with an ultralong 278 ns carrier lifetime, exceeding previous benchmarks by 2 orders of magnitude through meticulous Sn(IV) control. The nanocrystals demonstrate excellent colloidal stability, uniform monodispersity, and a distinct exciton peak. Central to these outcomes is our designed solid-liquid antioxidation suspension of tri-n-octylphosphine (TOP) and zerovalent tin (Sn(0)) that fully addresses the unique coexisting oxygen-driven and solvent-driven Sn oxidation mechanisms in Sn perovskite nanocrystal synthesis. We uncover the largely undervalued function of TOP in mitigating oxygen-driven Sn oxidation and introduce Sn(0) powder to generate a synergistic antioxidation function with TOP, significantly reducing Sn(IV)-induced defects and distortions and contributing to enhanced optoelectronic properties. Strikingly, this approach also profoundly impacts inorganic Sn-Pb perovskite nanocrystals, boosting lifetimes by 2 orders of magnitude and increasing photoluminescence quantum yield over 100-fold to 35%. Our findings illuminate the potential of Sn-based nanocrystals for optoelectronic applications.
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Further improvement of the performance and stability of inverted perovskite solar cells (PSCs) is necessary for commercialization. Here, ferrocene derivative dibenzoylferrocene (DBzFe) is used as an additive to enhance the performance and stability of MA- and Br- free PSCs. The results show that the introduction of DBzFe not only passivates the defects in the film but also inhibits the ion migration in the film. The final device achieves a power conversion efficiency (PCE) of 23.53%, which is one of the highest efficiencies currently based on self-assembled monolayers (SAMs). Moreover, it maintains more than 96.4% of the original efficiency when running continuously for 400 h at the maximum power point.
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This report is on the efficiency enhancement of wide bandgap lead halide perovskite solar cells (WBG Pb-PVK PSCs) consisting of FA0.8Cs0.2PbI1.8Br1.2 as the light-harvesting layer. WGB Pb-PVK PSCs have attracted attention as the top layer of all perovskite-tandem solar cells. Poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA), a conductive polymer, is always used as the hole transporting layer (HTL) for Pb-PVK PSCs. Nevertheless, the hydrophobic surface of the PTAA sometimes destroys the growth of the FA0.8Cs0.2PbI1.8Br1.2 film. On the other hand, the Fermi level of PTAA is not well matched with that of perovskite film. Thus, the PCE of the WBG Pb-based PSCs with PTAA as the HTL was not very high. In this report, the efficiency of the FA0.8Cs0.2PbI1.8Br1.2 is improved by passivating the surface of the PTAA with a monomolecular layer, where the surface becomes hydrophilic, and the band bending of the PTAA layer is improved to cause swift hole collection. Finally, WBG Pb-PVK PSCs (1.77 eV) with 16.52% efficiency are reported.
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A deep understanding of the effect of the A-site cation cross-exchange on the hot-carrier relaxation dynamics in perovskite quantum dots (PQDs) has profound implications on the further development of disruptive photovoltaic technologies. In this study, the hot carrier cooling kinetics of pure FAPbI3 (FA+ , CH(NH2 )2 + ), MAPbI3 (MA+ , CH3 NH3 + + ), CsPbI3 (Cs+ , Cesium) and alloyed FA0.5 MA0.5 PbI3 , FA0.5 Cs0.5 PbI3 , and MA0.5 Cs0.5 PbI3 QDs are investigated using ultrafast transient absorption (TA) spectroscopy. The lifetimes of the initial fast cooling stage (<1 ps) of all the organic cation-containing PQDs are shorter than those of the CsPbI3 QDs, as verified by the electron-phonon coupling strength extracted from the temperature-dependent photoluminescence spectra. The lifetimes of the slow cooling stage of the alloyed PQDs are longer under illumination greater than 1 sun, which is ascribed to the introduction of co-vibrational optical phonon modes in the alloyed PQDs. This facilitated efficient acoustic phonon upconversion and enhanced the hot-phonon bottleneck effect, as demonstrated by first-principles calculations.
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Zinc oxide (ZnO) nanowire (NW) based lead sulfide (PbS) quantum dot solar cells (QDSCs), i.e., bulk heterojunction QDSCs, have been widely investigated because of the excellent photoelectronic properties of PbS QDs and ZnO NWs. To further improve the efficiency of this type of QDSCs, various passivation methods are applied to ZnO NWs to suppress interface recombination caused by trap defects. However, the comparison among passivation using organic, inorganic, and inorganic-organic hybrid materials with different properties has been less studied. In this work, the effect of passivation with inorganic Mg-doped ZnO (ZMO), organic 1,2-ethanedithiol (EDT) and both of them on ZnO NWs and PbS QDSCs are investigated. As a result, ZnO NWs purely passivated by organic material EDT show the best performance with fewer surface defects and better matched energy level with the PbS QD layer. A nearly 1.7 times larger power conversion efficiency (PCE) of 6.9% is achieved for the solar device using ZnO NW @EDT, compared with that (4.1%) of the untreated one. The work provides a promising way to impede interlayer charge recombination and facilitate carrier transport, thus enhancing the photovoltaic performance of the device.
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Lead sulfur colloidal quantum dots (PbS CQDs) are a kind of IV-VI semiconductor nanocrystals which have attracted enormous interest in recent years because of their unique physicochemical properties. Controlling size, size distribution, and yield of PbS CQDs plays key priorities in order to improve their properties when they are applied in the photovoltaics and energy storage applications. Despite many systematical studies in PbS CQD syntheses with various perspectives, details of the formation mechanism impacted on the size, concentration, and size distribution of PbS CQDs in complicated reaction conditions remain poorly understood. In this work, an improved kinetic rate equation (IKRE) model is employed to describe PbS CQD formation under variable solution temperatures. After establishing the necessary discretized equations and reviewing the link between model parameters and experimental information, a parametric study is performed to explore the model's feature. In addition, a set of experimental data has been compared with the result of IKRE model fits, which would be used to obtain corresponding thermodynamic and kinetic parameters that can further affect the CQD growth over longer timescales. This method builds up the relationship between the nucleation and Ostwald ripening stage that would provide the possibility for future large-scale manufacturing of CQDs.