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Electronic and optical properties of two propounded compound in photovoltaic applications, CsPbI3 and CH3NH3PbI3: By DFT
摘要： Halide perovskite compounds are the serious contenders for conventional materials used in photovoltaic devices that will provide a bright future for solar cell industry. Therefore, preparing a comprehensive insight about their properties is necessary. In this regard, the electronic and optical studies of two important perovskite compound CsPbI3 and CH3NH3PbI3 in the cubic phase are performed by ?rst- principle method in Density Function Theory (DFT), using several approximations namely GGA, t-mbj and other types of t-mbj approximation with the tuned coef?cient including k-mbj and new mbj approximations. In addition to utilizing di?erent approximations, the e?ect of spin orbit coupling which is critical in these compounds, is evaluated in all of them to obtain realistic results. The band gaps calculated within new mbj approximation through spin orbit coupling are 1.34 eV and 1.49 eV for CsPbI3 and CH3NH3PbI3, respectively that unlike other DFT-based electronic calculations are in agreement with experimental results. Values of estimated e?ective masses of carriers represent lighter carriers for CH3NH3PbI3 in comparison to CsPbI3. Optical calculations of frequency dependent dielectric function con?rm non isotropic property in organic- inorganic perovskite CH3NH3PbI3 and estimate value of static refraction index equal to 2.47 which is in agreement with experimental measurements.
关键词： DFT,Optical properties,CsPbI3,CH3NH3PbI3,Photovoltaic applications
更新于2025-09-16 10:30:52
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Enhancing the Phase Stability of Inorganic α-CsPbI <sub/>3</sub> by the Bication-Conjugated Organic Molecule for Efficient Perovskite Solar Cells
摘要： Inorganic CsPbI3 perovskite has demonstrated promising potentials for photovoltaic applications, whereas the black perovskite polymorph (α phase) of CsPbI3 was easily prone to converting into yellow phase (δ phase) under ambient moist environment, which restrained its practical application and further studies severely. In this study, p-phenylenediammonium iodide (PPDI) was employed to posttreat CsPbI3 films for controlling the phase conversion, strengthening moisture resistance, and improving device performance. The multiple roles of PPDI were as follows: (1) avoiding spontaneous octahedral tilting by ionic bonds between NH3+ of PPD2+ and I? of [PbI6]4?; (2) enhancing the hydrophobicity induced by exactly exposed oil-wet (hydrophobic) benzene rings; and (3) passivating surface defects and filling I vacancies. As a result, after the treatment, mutable a-CsPbI3 could maintain its α phase for at least 30 d in dry air (<20% RH). The perovskite solar cells with PPDI treatment exhibited reproductive photovoltaic performance with a champion power conversion efficiency (PCE) of 10.4, and 91% of the initial PCE was retained after storage for 504 h in a dark dry box without any encapsulation.
关键词： solar cells,CsPbI3,posttreatment method,phase stability,inorganic perovskite
更新于2025-09-16 10:30:52
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Hybrid CdSe/CsPbI <sub/>3</sub> quantum dots for interface engineering in perovskite solar cells
摘要： Hybrid CdSe/CsPbI3 quantum dots (QDs) are selected for incorporation between the perovskite film and the hole transport layer (HTL). Owing to the high absorption coefficient and the suitable band gap of CsPbI3, an optimized energy level structure can be expected. Besides, energy transfer could be realized due to the overlap between the emission spectrum of CdSe QDs and the excitation spectrum of CsPbI3 QDs. Hence, CdSe/CsPbI3 QDs can serve as an interface layer to promote interfacial charge extraction and enhance light harvesting ability simultaneously. Compared with pristine perovskite solar cells (PSCs), hybrid CdSe/CsPbI3 QD incorporated PSCs achieve 21% enhancement in power conversion efficiency (PCE). The enhancement of PCE can be ascribed to the ultrafast charge carrier dynamics and F?rster resonance energy transfer (FRET) effect. The design of hybrid CdSe/CsPbI3 QDs offers an alternative method for interfacial engineering to enhance optical properties and facilitate the charge transport process in PSCs.
关键词： interface engineering,charge transport,perovskite solar cells,Hybrid CdSe/CsPbI3 quantum dots,F?rster resonance energy transfer
更新于2025-09-16 10:30:52
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Chemical Composition and Phase Evolution in DMAI-Derived Inorganic Perovskite Solar Cells
摘要： Cesium based inorganic perovskite CsPbI3 solar cells have attracted arising research interests due to its improved thermal stability and reduced ion immigration in comparison with their organic-inorganic counterparts. However, the preferred black perovskite CsPbI3 is thermodynamically unstable at room temperature, and it will spontaneously transform to the undesired non-photoactive yellow phase. The essence of the phase instability is the small size of Cs cation, which is not suitable to support the three-dimensional PbI3- framework. The large lattice strain induced from the ion size mismatch will drive the CsPbI3 lattice structure from three dimensional (3D) perovskite phases to one dimensional (1D) non-perovskite phase. Therefore, the improvement of the lattice symmetry and reduction of the lattice strain are the two directions to dissolve the problem of phase instability. The nanocrystal-induced phase stabilization is one strategy to reduce the lattice strain by increasing the surface area of the crystals in the film, which is normally realized by introducing organic long-chain alkyl amine in the precursor solution. The shortcoming of this method is its negative effect of a large number of grain boundaries on the carrier transport and injection. Currently, the most widely used and effective strategies are the DMAI related methods, including the DMAI additive methods and the HI derived methods. The HI derived methods, normally named HI additive, HI?PbI2 or HPbI3 precursor, are demonstrated inevitably bring the DMA byproduct in the precursor solution from the reaction between HI and DMF. Although there are already several works focused on the elaboration of the final perovskite layer with the pure inorganic phase or still the organic-inorganic composite, the conclusion is still a huge controversy. Therefore, whether the organic DMA cation exists, how much the organic DMA cation in the crystal lattice, the properties of the DMA/Cs mixed perovskite phase and the mechanism of the DMAI-assisted formation of the Cs base perovskite thin film are still unclear. In this work, we tracked the chemical composition, phase and bandgap of the perovskite layer during the thermal treatment. It was found that, with a controlled thermal annealing process, a more thermodynamically stable perovskite of mixed cation DMA0.15Cs0.85PbI3 could form with a certain amount of Cs4PbI6 residue. Unlike other mixed cation perovskite materials, the composition of DMA/Cs mixed perovskite is well fixed instead of a continuous component distribution. Further thermal annealing transformed the film into C(cid:26)(cid:4)(cid:14)(cid:18)/(cid:25)3 and then into D(cid:26)(cid:4)(cid:14)(cid:18)/(cid:25)3. The DMA0.15Cs0.85PbI3 phase exhibits a more symmetrical structure, a narrower bandgap, and superior phase stability than that of C(cid:26)(cid:4)(cid:14)(cid:18)/(cid:25)3. These findings will benefit the in-depth understanding of the properties of inorganic perovskite and their phase stability issue.
关键词： DMAI,inorganic perovskite,CsPbI3,phase stability,solar cells
更新于2025-09-12 10:27:22
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Visualizing and Suppressing Nonradiative Losses in High Open-Circuit Voltage n-i-p-Type CsPbI <sub/>3</sub> Perovskite Solar Cells
摘要： Since their first demonstration in PV devices in 2009, organic-inorganic hybrid metal halide perovskites have attracted tremendous attention because of their potential applications in solution-processed photovoltaics (PV). Many research efforts, such as composition engineering and interface engineering, have been dedicated to enhancing the power conversion efficiency (PCE) of perovskite-based solar cells (PSCs) to a high level of over 24%. However, operational stability issues remain a major challenge for organic-inorganic hybrid perovskites on the way towards commercialization. Alternatively, all-inorganic perovskites (CsPbX3, X = Cl, Br, I), have received increasing interest because they are theoretically stable up to their melting points (>300 °C). Especially, CsPbI3 in the cubic phase stands out because of the lowest bandgap (of ~1.75 eV) among the all-inorganic lead-based perovskites. Compared to all other all-inorganic lead-based perovskite halide semiconductors materials which have bandgaps higher than 1.90 eV, the 1.75 eV bandgap CsPbI3 is able to absorb slightly more light in the visible region and nominally is an excellent candidate for the front cell in tandem architectures with silicon as the back cell.
关键词： open-circuit voltage,CsPbI3,perovskite solar cells,interface engineering,non-radiative losses,bulk passivation
更新于2025-09-12 10:27:22
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Spray‐Coated Colloidal Perovskite Quantum Dot Films for Highly Efficient Solar Cells
摘要： A fully automated spray-coated technology with ultrathin-film purification is exploited for the commercial large-scale solution-based processing of colloidal inorganic perovskite CsPbI3 quantum dot (QD) films toward solar cells. This process is in the air outside the glove box. To further improve the performance of QD solar cells, the short-chain ligand of phenyltrimethylammonium bromide (PTABr) with a benzene group is introduced to partially substitute for the original long-chain ligands of the colloidal QD surface (namely PTABr-CsPbI3). This process not only enhances the carrier charge mobility within the QD film due to shortening length between adjacent QDs, but also passivates the halide vacancy defects of QD by Br? from PTABr. The colloidal QD solar cells show a power conversion efficiency (PCE) of 11.2% with an open voltage of 1.11 V, a short current density of 14.4 mA cm?2, and a fill factor of 0.70. Due to the hydrophobic surface chemistry of the PTABr–CsPbI3 film, the solar cell can maintain 80% of the initial PCE in ambient conditions for one month without any encapsulation. Such a low-cost and efficient spray-coating technology also offers an avenue to the film fabrication of colloidal nanocrystals for electronic devices.
关键词： CsPbI3,perovskite,colloidal quantum dots,spray coating,solar cells
更新于2025-09-11 14:15:04
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Pseudohalide (SCN <sup>?</sup> )-doped CsPbI <sub/>3</sub> for high-performance solar cells
摘要： Cesium lead halide CsPbI3 is regarded as a promising material to solve the issues of material decomposition and ion migration caused by the organic group in organic–inorganic hybrid perovskite solar cells (PSCs) under operating conditions. However, there are many defects in a pure CsPbI3 material and its cubic phase (a-phase) is thermodynamically unstable, which will prevent a high device performance. Here, we incorporated the pseudohalide ion SCN(cid:2) in a CsPbI3 thin film to improve the crystallinity with smooth perovskite films. The results of XRD and PL showed that the crystallization property of the CsPbI3 thin films with the addition of Pb(SCN)2 exhibited a huge improvement compared to the reference. The champion power conversion efficiency (PCE) of CsPbI3 PSCs with the optimized Pb(SCN)2 additive (2%) could reach as high as 17.04%. In addition, the CsPbI3 films with the Pb(SCN)2 additive exhibited higher thermal stability than the reference one.
关键词： pseudohalide,CsPbI3,solar cells,thermal stability,Pb(SCN)2
更新于2025-09-11 14:15:04
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Bifunctional Ytterbium (III) Chloride Driven Low‐Temperature Synthesis of Stable α‐CsPbI <sub/>3</sub> for High‐Efficiency Inorganic Perovskite Solar Cells
摘要： Inorganic perovskite CsPbI3 has been studied as a promising alternative light-absorbing material for photovoltaic application due to its suitable band gap for converting solar light and enhanced stability toward ambient conditions compared to the organic–inorganic halide perovskite. However, the photoactive α-phase of CsPbI3 can only be stabilized at a high temperature and the phase transition from α-phase to δ-phase easily occurs at room temperature. Herein, ytterbium (III) chloride (YbCl3) as a bifunctional additive is introduced into the perovskite precursor to stabilize the black α-phase, and high-quality CsPbI3 films are obtained at a temperature as low as 80 °C. Yb3+ partly replaces Pb2+ to enhance the tolerance factor and favors the formation of α-phase. The Lewis adduct complex of YbCl3·DMSO in the perovskite film can passivate the perovskite film with reduced defects and help enhance the stability of the α-phase. The YbCl3-modified planar-type α-CsPbI3 perovskite solar cells show a champion power conversion efficiency of 12.4% with an impressive stability at ambient conditions. The additive induced controlled crystallization provides a simple and promising way to improve the photovoltaic performance of inorganic perovskite solar cells.
关键词： CsPbI3,inorganic perovskite,solar cells,ytterbium (III) chloride
更新于2025-09-11 14:15:04
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Rhenium diselenide as the broadband saturable absorber for the nanosecond passively Q-switched thulium solid-state lasers
摘要： Although the solar cells based on the α-CsPbI3 presents very impressive power conversion efficiency, it suffers from insufficient crystalline structure stability even in ambient condition. Herein, the black orthorhombic γ phase based CsPbI3 is successfully fabricated with its performance further optimized by doping chlorine ions. It is found that the chlorine incorporation improves crystallization dynamics for favorable surface morphology and crystalline orientation. In particular by doping 3 mol% chlorine into the γ-CsPbI3 film, its trap density is minimized with enhanced black phase stability and much improved thin film characteristics, including conductivities, electron and hole mobilities. Consequently, the solar cell efficiency is increased to as high as 16.07%. More importantly, the PCE of the optimized device shows only 0.45% degradation after continuous light soaking for 200 h. It retains as much as 94% of its initial PCE even after being exposed in air (relative humidity of 20–30% at 25 °C) for 60 days.
关键词： Chlorine,Solar cells,Efficiency,Stability,γ-CsPbI3
更新于2025-09-11 14:15:04
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δ‐CsPbI <sub/>3</sub> Intermediate Phase Growth Assisted Sequential Deposition Boosts Stable and High‐Efficiency Triple Cation Perovskite Solar Cells
摘要： Cs/FA/MA triple cation perovskite films have been well developed in the antisolvent dripping method, attributable to its outstanding photovoltaic and stability performances. However, a facile and effective strategy is still lacking for fabricating high-quality large-grain triple cation perovskite films via sequential deposition method a, which is one of the key technologies for high efficiency perovskite solar cells. To address this issue, a δ-CsPbI3 intermediate phase growth (CsPbI3-IPG) assisted sequential deposition method is demonstrated for the first time. The approach not only achieves incorporation of controllable cesium into (FAPbI3)1–x(MAPbBr3)x perovskite, but also enlarges the perovskite grains, manipulates the crystallization, modulates the bandgap, and improves the stability of final perovskite films. The photovoltaic performances of the devices based on these Cs/FA/MA perovskite films with various amounts of the δ-CsPbI3 intermediate phase are investigated systematically. Benefiting from moderate cesium incorporation and intermediate phase-assisted grain growth, the optimized Cs/FA/MA perovskite solar cells exhibit a significantly improved power conversion efficiency and operational stability of unencapsulated devices. This facile strategy provides new insights into the compositional engineering of triple or quadruple cation perovskite materials with enlarged grains and superior stability via a sequential deposition method.
关键词： CsPbI3 intermediate phase growth,stability,perovskite solar cells,sequential deposition,triple cation perovskite,grain growth
更新于2025-09-11 14:15:04