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The practical applications of perovskite solar cells (PSCs) are limited by the further improvement of their stability and performance. Interface engineering is a promising strategy to solve these pain points. Herein, we design (R)-(-)-1-cyclohexylethylamine iodide (R-CEAI), composed of positively charged hydrophobic R-CEA

Surface enhanced Raman scattering (SERS) is a rapid and nondestructive technique that is capable of detecting and identifying chemical or biological compounds. Sensitive SERS quantification is vital for practical applications, particularly for portable detection of biomolecules such as amino acids and nucleotides. However, few approaches can achieve sensitive and quantitative Raman detection of these most fundamental components in biology. Herein, a noble-metal-free single-atom site on a chip strategy was applied to modify single tungsten atom oxide on a lead halide perovskite, which provides sensitive SERS quantification for various analytes, including rhodamine, tyrosine and cytosine. The single-atom site on a chip can enable quantitative linear SERS responses of rhodamine (10Supplementary material is available for this article at 10.1007/s40843-022-1968-5 and is accessible for authorized users.表面增强拉曼散射(SERS)是一种快速且无损的化学和生物分子检测技术. 高灵敏且定量化的SERS检测技术对其在实际中的应用至关重要, 尤其是对生物分子如氨基酸和碱基的便携化检测. 但是鲜有技术手段能够实现对这些最基本的生物分子进行高灵敏且定量化的拉曼检测. 我们提出了一种无需贵金属的单原子位点修饰芯片策略, 用钨单原子氧化物修饰铅卤钙钛矿芯片, 实现了多种检测物的高灵敏定量化识别, 包括罗丹明、 酪氨酸和胞嘧啶. 芯片上单原子位点技术能够实现对罗丹明、 酪氨酸和胞嘧啶的线性检测, 相应的定量化区间分别为: 10

Single crystal (SC) MAPbBr3 perovskite is regarded as a promising material to fabricate high-performance photodetectors (PDs) due to its impressive optoelectronic properties and good chemical stability. Cs+ doping has been proved to be an effective method to significantly improve the optoelectronic properties of MAPbBr3 SC. However, the intrinsic effect of Cs+ on the crystal structure is still unclear. Herein, we grew a series CsxMA(1-x)PbBr3 SCs. X-ray rocking curves (XRC) of CsxMA(1-x)PbBr3 SCs prove that appropriate Cs-doping concentration could reduce defect density effectively. X-ray photoelectron spectroscopy (XPS) measurements indicate that Cs-doping enhances the atoms interaction in CsxMA(1-x)PbBr3 lattice due to isoelectronic impurity effect. Single-crystal PDs were fabricated to compare the optoelectronic properties of MAPbBr3 SCs with different Cs-doping concentration, and the 2% Cs-doped CsxMA(1-x)PbBr3 PD shows the optimum performance. Density functional theory (DFT) calculations demonstrate that Cs-doping leads to lattice relaxation effect which is benefit to reduce trap density of CsxMA(1-x)PbBr3 SCs. The Pb-6p level of CsxMA(1-x)PbBr3 slightly shifts to lower energy region compared with MAPbBr3, resulting in the decrease of band gap of CsxMA(1-x)PbBr3.

Photocapacitor integrating both energy harvest and storage functions into a single device is a frontier research orientation, which facilitates the efficient and sustainable utilization of green energy. However, the multi-functions in one device and structural complexity of the integrated device, particularly the mismatch between energy harvest and storage units, lead to a relatively large energy loss in the energy storage and output processes. Here, we design a voltage adjustable hybrid supercapacitor (VAHSC) as an energy storage unit of a three-terminal photocapacitor. The VAHSC effectively harmonizes the energy harvest and storage units, resulting in the current, voltage, power, and energy match between both units. The optimal photocapacitor achieves a storage efficiency as high as 98.28% and Joule efficiency of 86.01%, along with excellent charge/discharge cycle stability. The great leap in this efficiency marks a substantial step towards the practical application of solar-charging energy storage integrated devices.

Although the best research-cell efficiency (>25%) of perovskite solar cells (PSCs) is comparable with that of silicon solar cells, the industrial application of PSCs is limited by the further improvement of performance and stability. Here, cesium acetate (CsAc) is introduced into lead iodide (PbI2) precursor, which tunes the morphology and structure of PbI2 and promotes the conversion of PbI2 into stable large perovskite grains. Moreover, the introduction of Cs+ and Ac− can fill up the FA+, I− vacancy and combine with uncoordinated Pb2+, which reduces the trap density. The CsAc introduction not only optimizes the quality of perovskite films, but also reduces the defects in the bulk phase, which facilitates the transportation of carriers and mitigates non-radiative recombination. Consequently, the CsAc optimized PSCs achieve a maximum power conversion efficiency (PCE) of 22.01%. Meanwhile, the unsealed device still maintains an initial PCE of 96% after being exposed in the air for 45 days.

The practical applications of perovskite solar cells (PSCs) are limited by further improvement of their stability and performance. Additive engineering and interface engineering are promising medicine to cure this stubborn disease. Herein, an alkali metal fluoride as an additive is introduced into the tin oxide (SnO2) electron transport layer (ETL). The formation of coordination bonds of F- ions with the oxygen vacancy of Sn4+ ions decreases the trap-state density and improves the electron mobility; the hydrogen bond interaction between the F ion and amine group (FA+) of perovskite inhibits the diffusion of organic cations and promotes perovskite (PVK) stability. Meanwhile, the alkali metal ions (K+, Rb+, and Cs+) permeated into PVK fill the organic cation vacancies and ameliorate the crystal quality of PVK films. Consequently, a SnO2-based planar PSC exhibits a power conversion efficiency (PCE) of 20.24%, while the PSC modified by CsF achieves a PCE of 22.51%, accompanied by effective enhancement of stability and negligible hysteresis. The research results provide a typical example for low-cost and multifunctional additives in high-performance PSCs.

Hole transporting materials (HTMs) play an unparalleled role in heightening the stability and photovoltaic performance of perovskite solar cells (PSCs). The organic small molecule spiro-OMeTAD is frequently utilized for HTM in PSCs. However, the raw spiro-OMeTAD without dopant would be harmful to the development of highly efficient PSCs, due to its unsatisfied hole mobility and conductivity. Therefore, we introduce an inorganic dopant (chromium trioxide, CrO3) into the lithium-salt doped spiro-OMeTAD. Because of the exclamatory oxidizability of CrO3, it can accelerate the oxidation of spiro-OMeTAD and thereby enhancing the hole mobility of HTM. The introduction of CrO3 not only substantially decreases the density of defects, but also adjusts spiro-OMeTAD energy band, and thus effectively suppresses the hysteresis and improving stability of PSCs. In the end, we obtained a power conversion efficiency (PCE) as high as 22.6% after doping CrO3 in spiro-OMeTAD. The facile, low cost and outstanding photovoltaic performance render CrO3 an excellent dopant for HTMs in PSCs.

Interface engineering has been widely applied to perovskite solar cells (PSCs) for solving the problems caused by high density of parasitic traps and the defects that exist at grain boundaries and surfaces. Various inorganic metal oxides play roles in PSCs, helping to achieve higher efficiency and better long-term stability. In this work, two-phase hydrothermal method is used for CoFe2O4 nanocrystals (NCs) synthesis and the obtained NCs were used to modify the surface between perovskite (PVK) and hole transport layer (HTL). Results show that CoFe2O4 modified devices have enhanced hole extraction, reduced trap density, and hydrophobic ligand connected to CoFe2O4 NCs provide better moisture resistance to PVK layer. Devices with CoFe2O4 layer exhibit a best PCE of 19.65% with improved open circuit voltage (VOC), fill factor (FF) and reproducibility. At steady-state, CoFe2O4 modified devices show a current density of 20.16 mA/cm2 and PCE of 18.97%.

Doping dopants are one of the most effective methods which can improve crystallinity, reduce traps, adjust bandgap width of perovskite films and obtain efficient perovskite photodetectors. Chlorine-based dopants have been reported in many literatures, yet their role still remains a mystery. In our study, a typical solution-processed organic–inorganic hybrid perovskite material CH3NH3PbI3 (MAPbI3) was synthesized as the absorption layer for photodetectors and methylammonium chloride (MACl) was selected as dopant. By tuning the incorporation ratios of MACl in the MAPbI3 precursor solutions, bandgap width and trap densities of the MAPbI3 films can be effectively reduced. The crystallinity and morphology of perovskite films were obviously improved, and the photoelectric properties of photodetectors were further enhanced. Ultimately, the optimal device was obtained when the incorporation ratio of MACl reached 1.0 wt%. External quantum efficiency (EQE) of the optimal device exhibited up to 81%, nearly 30% higher than EQE of the device without incorporation. A lower dark current density (Jd) of 8.4 × 10–8 A cm−2 at − 0.1 V bias was obtained because of low trap densities, moreover, due to the suppressed Jd, the optimal device operating at room temperature showed a specific detectivity (D*) of 2.71 × 1012 Jones and a linear dynamic range (LDR) of 104 dB, higher than the D* of 7.03 × 1011 Jones and the LDR of 91 dB of the device without incorporation, respectively.

Perovskite solar cells have developed rapidly in the past decades. However, there are large amounts of ionic defects at the surface and grain boundaries of perovskite films which are detrimental to both the efficiency and stability of perovskite solar cells. Here, an organic halide salt pyridinium iodide (PyI) is used in cation–anion-mixed perovskite for surface defect passivation. Different from the treatment with Lewis base pyridine (Py) which can only bind to the under-coordinated Pb ions, zwitterion molecule PyI can not only fill negative charged iodine vacancies, but also interact with positive charged defects. Compared with Py treatment, PyI treatment results in smoother surface, less defect densities and non-radiative recombination in perovskite, leading to an improved VOC, negligible J–V hysteresis and stable performance of devices. As a result, the champion PyI-treated planar perovskite solar cell with a high VOC of 1.187 V achieves an efficiency of 21.42%, which is higher than 20.37% of Py-treated device, while the pristine device without any treatment gets an efficiency of 18.83% at the same experiment conditions.

Regardless of the impressive progress that perovskite solar cells (PSCs) have achieved, especially considering their power conversion efficiency (PCE) over 25%, traditional PSCs still contend with an inherent instability with exposure to humidity, which remains as a critical issue for the realization of commercial production. Herein, we proposed an effective pathway to relieve the instability of PSCs without sacrificing efficiency by introducing a 2D phase at the surface of the 3D perovskite film, based on a novel organic cyclohexylmethylammonium iodide (CMAI). The self-assembled thin 2D capping layer atop the 3D perovskite layer can not only reduce the ionic defects, but also serve as a protective barrier against moisture. Consequently, the champion device incorporating 2D perovskite capping layers delivered an open-circuit voltage (Voc) of 1.19 V, which contributes to an impressive PCE of 22.06% on account of the improved charge extraction and decreased non-radiative recombination. More importantly, an excellent long-term stability along with mitigated hysteresis was observed for the modified devices as a result of the suppressed ion migration and high humidity resistance of the 2D perovskite film. Our finding provides a comprehensive approach for simultaneously enhancing the efficiency and stability of PSCs through dimension engineering utilizing CMA-based 2D perovskite materials.

Spiro-OMeTAD has been widely employed as one of the most frequently used hole transport materials (HTMs) for high-performance perovskite solar cells (PSCs). Nevertheless, raw spiro-OMeTAD suffers from inferior electronic properties. To date, doping has been considered to be a promising strategy to address this dilemma. In this work, we successfully introduce K3[Fe(CN)6], a cheap and effective inorganic oxidant, into spiro-OMeTAD together with lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and 4-tert-butylpyridine (tBP) for highly efficient PSCs. The addition of the dopant K3[Fe(CN)6] could not only promote the oxidation of spiro-OMeTAD to generate a higher hole density, but also adjust its highest occupied molecular orbital (HOMO) to pursue an appropriate energy level alignment with the perovskite active layer, resulting in a high conductivity and hole extraction ability of spiro-OMeTAD. As a consequence, the PSC incorporated with K3[Fe(CN)6] achieves a champion efficiency of 20.84%, which is higher than that of the undoped device (18.09%). Furthermore, the K3[Fe(CN)6]-doped devices demonstrate an enhanced reproducibility and alleviated hysteresis. Our results indicate that K3[Fe(CN)6] is an efficient and facile dopant of spiro-OMeTAD for highly efficient and stable PSCs.

Machine fault detection has great practical significance. Compared with the detection method that requires external sensors, the detection of machine fault by sound signal does not need to destroy its structure. The current popular audio-based fault detection often needs a lot of learning data and complex learning process, and needs the support of known fault database. The fault detection method based on audio proposed in this paper only needs to ensure that the machine works normally in the first second. Through the correlation coefficient calculation, energy analysis, EMD and other methods to carry out time-frequency analysis of the subsequent collected sound signals, we can detect whether the machine has fault.

The convenience of "no installation, available at your fingertips" of the WeChat small program makes it unique in the application of mobile terminal auxiliary experimental teaching. In order to optimize the assessment system and improve the quality and outcomes of experimental teaching, a self-designed WeChat small program was used to assist the development of the process assessment system. This system was applied to the teaching practice of "Experiment of Inorganic Chemistry" course for the first-year undergraduates majored in Biological Engineering, with the aim to promote teaching and learning by assessment. The results showed that course scores of the students who used this small program were superior to the control group and the correlation between the process assessment and final examination results was significant. These results indicated the WeChat small program assisted process assessment could effectively improve the learning outcomes of students, enable them to grasp the knowledge of Experiment of Inorganic Chemistry efficiently. The results of the questionnaire for the teachers and students also showed a high recognition of the WeChat small program assisted teaching.

Improving stability is a major aspect for commercial application of perovskite solar cells (PSCs). The all-inorganic CsPbBr3 perovskite material has been proven to have excellent stability. However...

Although perovskite solar cells (PSCs) have achieved the highest power conversion efficiency (PCE) of 25.2% in a very short period of development, they suffer from poor stability because the organic–inorganic hybrid perovskite materials are easily decomposed under the attacks of oxygen, moisture, heat and ultraviolet light. It is demonstrated that an all inorganic perovskite material of CsPbBr3 has excellent stability against moisture, oxygen and heat, but it has a slightly wide bandgap of 2.3 eV, which seriously hinders light absorption and leads to poor PCE. Metal ion doping is a good approach to overcome this drawback because it can effectively tune the bandgap, enhance light absorption, suppress trap states and adjust the energy level. Here, we use the CoBr2 doping route to fabricate high quality and crystallinity CoBr2 doped CsPbBr3 film. As a result, a champion device with the CsPb0.998Co0.002Br3 film yields a PCE as high as 8.57%, much higher than that of the pristine CsPbBr3 one (6.81%). It is found that the lower number of trap defects and higher carrier density of the CsPb0.998Co0.002Br3 film are key reasons for the enhancement because they bring about better charge carrier dynamics and suppressed dark recombination.