Publications by authors named "Shuzi Hayase"

The exploration of nontoxic Sn-based perovskites as a viable alternative to their toxic Pb-based counterparts has garnered increased attention. However, the power conversion efficiency of Sn-based perovskite solar cells lags significantly behind their Pb-based counterparts. This study presents a ternary passivation strategy aimed at enhancing device performance, employing [6,6]-phenyl-C61-butyric-acid-methyl-ester (PCBM), poly(3-hexylthiophene) (P3HT), and indene C60 bisadduct (ICBA).

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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.

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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.

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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.

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CsNaInCl double perovskites, which have excellent photoelectric conversion properties and are non-toxic and lead-free, have recently gained significant attention. In particular, double-perovskite quantum dots (QDs) are viewed as a promising material for optoelectronic device applications. Ligands such as oleic acid (OA) and oleylamine (OAm) are essential for the synthesis of perovskite QDs, but their specific roles in double-perovskite QDs remain unclear.

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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 CsSnI nanocrystals with an ultralong 278 ns carrier lifetime, exceeding previous benchmarks by 2 orders of magnitude through meticulous Sn(IV) control.

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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.

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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 FACsPbIBr 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.

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The photoelectric properties of nontoxic Sn-based perovskite make it a promising alternative to toxic Pb-based perovskite. It has superior photovoltaic performance in comparison to other Pb-free counterparts. The facile oxidation of Sn to Sn presents a notable obstacle in the advancement of perovskite solar cells that utilize Sn, as it adversely affects their stability and performance.

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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 FAPbI (FA , CH(NH ) ), MAPbI (MA , CH NH ), CsPbI (Cs , Cesium) and alloyed FA MA PbI , FA Cs PbI , and MA Cs PbI 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 CsPbI QDs, as verified by the electron-phonon coupling strength extracted from the temperature-dependent photoluminescence spectra.

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Methylammonium lead iodide (MAPbI) perovskite quantum dots (QDs) have become one of the most promising materials for optoelectronics. Understanding the dynamics of the charge transfer from MAPbI QDs to the charge transport layer (CTL) is critical for improving the performance of MAPbI QD photoelectronic devices. However, there is currently less consensus on this.

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The excellent optoelectronic properties of tin halide perovskites (Sn-PVKs) have made them a promising candidate for replacing toxic Pb counterparts. Concurrently, their enormous potential in photon harvesting and thermoelectricity applications has attracted increasing attention. The optoelectronic properties of Sn-PVKs are governed by the flexible nature of SnI octahedra, and they exhibit extremely low thermal conductivity.

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CsPbI quantum dots (QDs) are of great interest in new-generation photovoltaics (PVs) due to their excellent optoelectronic properties. The long and insulative ligands protect their phase stability and enable superior photoluminescence quantum yield, however, limiting charge transportation and extraction in PV devices. In this work, we use a fullerene derivative with the carboxylic anchor group ([SAM]C60) as the semiconductor ligand and build the type II heterojunction system of CsPbI QDs and [SAM]C60 molecules.

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Lead-free tin perovskite solar cells (PKSCs) have attracted tremendous interest as a replacement for toxic lead-based PKSCs. Nevertheless, the efficiency is significantly low due to the rough surface morphology and high number of defects, which are caused by the fast crystallization and easy oxidization. In this study, a facile and universal posttreatment strategy of sequential passivation with acetylacetone (ACAC) and ethylenediamine (EDA) is proposed.

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Article Synopsis
  • Perovskite solar cells (PSCs) have made great progress in efficiency and stability, but improving these aspects remains challenging.
  • The study introduces a functional additive called 3-mercaptopropyltriethoxysilane (SiSH), which helps reduce film stress, decrease defects, and prevent lead leakage in PSCs.
  • Implementation of SiSH has increased power conversion efficiency from 20.80% to 22.42% and improved device stability, while also utilizing new adsorbents to address lead leakage for environmental safety.
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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.

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Sn halide perovskite solar cells (PKSCs) are the most promising competitors to conventional lead PKSCs. Nevertheless, defects at the surfaces and grain boundaries hinder the improvement of the PKSCs' performance. Liquid surface passivation on the perovskite layer is commonly used to decrease these defects.

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Overcoming loss to increase the efficiency of perovskite solar cells (PSCs) has been aggressively studied. In this work, we introduce and compare rubidium iodide (RbI) and potassium iodide (KI) alkali metal halides (AMHs) as dopants in a tin-lead (SnPb)-based perovskite system to improve the performance of PSCs by enhancing their . Improvement in terms of surface morphology, crystallinity, charge transfer, and carrier transport in the SnPb perovskites was observed with the addition of AMH dopants.

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To develop high-performance thermoelectric devices that can be created using printing technology, the interface of a composite material composed of MASnI and BiTe, which individually show excellent thermoelectric performance, was studied based on first-principles calculations. The structural stability, electronic state, and interfacial thermal conductance of the interface between BiTe and MASnI were evaluated. Among the interface structure models, we found stable interface structures and revealed their specific electronic states.

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Solution-processed colloidal quantum dot solar cells (CQDSCs) is a promising candidate for new generation solar cells. To obtain stable and high performance lead sulfide (PbS)-based CQDSCs, high carrier mobility and low non-radiative recombination center density in the PbS CQDs active layer are required. In order to effectively improve the carrier mobility in PbS CQDs layer of CQDSCs, butylamine (BTA)-modified graphene oxide (BTA@GO) is first utilized in PbS-PbX (X = I, Br) CQDs ink to deposit the active layer of CQDSCs through one-step spin-coating method.

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The composition and crystallization process are essential for high-quality perovskite films. Cesium (Cs) and methylammonium chlorine (MACl) were found to affect the crystallization kinetics of perovskite, and the performance and stability of corresponding devices were greatly improved. We adopted an ion exchange method to remove MACl vapor and add Cs to form a multiple-cation-based perovskite film.

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Compositional engineering and interfacial modifications have played pivotal roles in the accomplishment of high-efficiency perovskite solar cells (PSCs). Different interfaces in the PSCs influence the performance remarkably either by altering the crystallization of the active material or shifting the energy levels or improving the electrical contact. This work reports how a thin layer of cesium acetate on the TiO electron transport layer (ETL) induces generation of a PbI-rich methylammonium lead iodide (MAPbI) composition at the ETL/MAPbI interface, which downshifts the conduction band level of MAPbI to create an energy level gradient favorable for carrier collection, resulting in higher photocurrent, fill factor, and overall power conversion efficiency.

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CsPbIBr perovskite solar cells have attracted much attention because of the rapid development in their efficiency and their great potential as a top cell of tandem solar cells. However, the outputs observed so far in most cases are far from that desired for a top cell. Up to now, with various kinds of treatments, the reported champion is only 1.

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Article Synopsis
  • Nickel oxide (NiO) thin films are being explored as a substitute for expensive and unstable organic materials in inverted planar perovskite solar cells (IP-PSCs) due to their efficiency as hole transport layers (HTL).
  • The study introduces aluminum-doped nickel oxide (ANO) films, which significantly improve electrical conductivity and reduce energy losses, resulting in better performance for IP-PSCs.
  • ANO HTL with 5% doping achieved a power conversion efficiency (PCE) of 20.84%, surpassing previous NiO-based designs, and showed enhanced stability, improving performance by 11% after 1728 hours of storage.
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