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Abstract Methylammonium chloride (MACl) additive is almost irreplaceable in high‐performance formamidine perovskite photovoltaics. Nevertheless, Some of the problems that can arise from adding MACl are rarely mentioned. Herein, it is proposed for the first time that the addition of MACl would cause the non‐stoichiometric ratio in the perovskite film, resulting in the halogen vacancy. It is demonstrated that the non‐synchronous volatilization of methylamine cations and chloride ions leads to the formation of halogen vacancy defects. To solve this problem, the NH4HCOO is introduced into the perovskite precursor solution to passivate the halogen vacancy. The HCOO− ions have a strong force with lead ions and can fill the halogen vacancy defects. Consequently, the champion devices' power conversion efficiency (PCE) can be improved from 21.23% to 23.72% with negligible hysteresis. And the unencapsulated device can still retain >90% of the initial PCE even operating in N2 atmosphere for over 1200 h. This work illustrates another halogen defect source in the MACl‐assisted formamidine perovskite photovoltaics and provides a new route to obtain high‐performance perovskite solar cells.

Improvement of performance and cost reduction are urgent issues for proton exchange membrane water electrolyzers (PEMWEs). This study explored ways to improve electrolyzer performance from the perspective of the catalyst layer (CL) microstructures. The pore network model of the CL was established, and the obtained structural, mass transfer and electrochemical parameters were coupled with the macroscale performance model of PEMWE to get the multi-scale performance model. The mass transfer, heat transfer, and electrochemical processes inside the electrolyzer were considered to improve the model's accuracy. The maximum error between the simulated results by this multi-scale performance model and the experimental data was verified to be only 3.1%. The verified model was then used to predict the electrolyzer performance with various cathode/anode catalyst layer (CCL/ACL) microstructures. The predicted results showed that the electrochemical activity surface area affects the performance of PEMWE to a much greater extent than the conductivity. The performance of PEMWE gradually deteriorated as the catalyst particle radius or pore diameter of the CCL/ACL increased by the same degree, and the catalyst particle radius had a relatively more significant impact on the performance of the electrolyzer. Overall, the variation of ACL structure had a more substantial effect on the electrolyzer performance than that of CCL.

Van der Waals ZnO/MoS2 heterostructure has been experimentally demonstrated as one of the potential candidates for photocatalyst, however, the charge carrier dynamics upon photoexcitation still remains unclear. By using nonadiabatic molecular dynamics simulations, we mainly focus on the influences of interfacial point defects on photogenerated charge separation in the ZnO/MoS2. The results reveal that oxygen vacancy in ZnO layer can induce a higher hole transfer efficiency compared to the pristine ZnO/MoS2, which attributes to the enhanced nonadiabatic coupling, originating from an out-of-plane vibration mode of S atoms, a decreased energy gap for intralayer hole transfer and stronger energy state oscillation. Alternatively, S vacancy in MoS2 introducing additional energy states in the band gap of ZnO/MoS2, serves as charge carrier recombination channels, and significantly reduces charge carrier lifetime, while doping O atom in S vacancy can compensate this effect. This study provides helpful guidance to design functional devices for solar energy photovoltaic conversion, based on two-dimensional ZnO/MoS2 heterostructures.

Energy transfer plays an essential role in inorganic semiconductor nanocrystal-chromophore hybrids which show potential applications in light collection and emitting. The understanding of the fundamental mechanics of energy transfer processes is vital to enhance the performance of light-harvesting optoelectronic devices. Here we report the effect of varying donor sizes on energy transfer from perovskite nanocrystals to chromophore molecules. Both single energy transfer and triplet transfer mechanisms have been identified to occur between CsPbBr3 quantum dots linked to a Rhodamine B dye. The ease of adjusting optical properties via particle-size controlling provides a particular platform to accommodate excited-state couplings in perovskite-chromophore hybrids.

Tpx3Cam is a newly developed time-stamped camera. With the ability to record the arrival time and position of each event simultaneously, it becomes a powerful tool in atomic and molecular research. As an inherent weakness, the time-walk effect resulting in a deviation in the arrival time is a major obstacle in improving the experimental resolution and reconstruction of momentum along the time-of-flight. We developed an analytic expression to describe and correct the time-walk effect, which is independent of different fragments once the parameters of the spectrometer, the microchannel plate (MCP), the phosphor screen, and the Tpx3Cam, such as voltages on the spectrometer and MCP, are fixed. With the time-walk correction, 3D momentum distributions of N+ and N2+ from the N2 molecule’s Coulomb explosion were well extracted, paving a way for filming molecular dynamics in three dimensions with time-stamped velocity map imaging. Simultaneously, a denoising method based on data filtering is presented for Tpx3Cam.

Abstract Carbon nanodots (CDs) have emerged as an alternative option for traditional nanocrystals due to their excellent optical properties and low toxicity. Nevertheless, high emission efficiency is a long‐lasting pursuit for CDs. Herein, CDs with near‐unity emission efficiency are prepared via atomic condensation of doped pyrrolic nitrogen, which can highly localize the excited states thus lead to the formation of bound excitons and the symmetry break of the π–electron conjugation. The short radiative lifetimes (

Performance of perovskite LED tends to decline as the active area increases, thus understanding the failure mechanism is paramount to surmount this limitation. Here, the authors report severe phase-segregation to be the cause, and introduce L-Norvaline to overcome it, as the result, highly-efficient 9.0 cm2 green PeLED is realised.

Abstract Intramolecular exciton dissociation is critical for high efficient mobile charge carrier generations in organic solar cells. Yet despite much attention, the effects of π bridges on exciton dissociation dynamics in donor–π–acceptor (D-π-A) alternating conjugated polymers remain still unclear. Here, using a combination of femtosecond time-resolved transient absorption (TA) spectroscopy and steady-state spectroscopy, we track ultrafast intramolecular exciton relaxation dynamics in three D-π-A alternating conjugated polymers which were synthesized by Qin's group and named HSD-A, HSD-B, HSD-C. It is found that the addition of thiophene unit as π bridges will lead to the red shift of steady-state absorption spectrum. Importantly, we reveal the existence of a new intramolecular exciton dissociation pathway mediated by a bridge-specific charge transfer (CT′) state with the TA fingerprint peak at 1200 nm in π-bridged HSD-B and HSD-C. This CT′ state results in higher electron capture rates for HSD-B and HSD-C as compared to HSD-A. Depending on the proportion of CT′ state and nongeminate recombination are important step for the understanding of high power conversion efficiencies in HSD-B than in HSD-C. We propose that this bridge-specific exciton dissociation pathway plays an important role in ultrafast intramolecular exciton dissociation of organic photovoltaic material D-π-A alternating conjugated polymers.

Designing efficient perovskite light-emitting diodes remains a challenge due to the strong Auger recombination and resulting Joule heating. Here, the authors propose polarizable p-fluorophenethylammonium to generate quasi-2D perovskites with reduced binding energy developing perovskite light-emitting diodes with a peak EQE of 20.36% and a maximum luminance of 82,480 cdm-2.

Abstract Flexible perovskite solar cells (FPSCs) represent a promising technology in the development of next‐generation photovoltaic and optoelectronic devices. SnO2 electron transport layers (ETL) typically undergo significant cracking during the bending process of FPSCs, which can significantly compromise their charge transport properties. Herein, the semi‐planar non‐fullerene acceptor molecule Y6 (BT‐core‐based fused‐unit dithienothiophen [3,2‐b]‐pyrrolobenzothiadiazole derivative) is introduced as the buffer layer for SnO2‐based FPSCs. It is found that the Y6 buffer layer can enhance the ability of charge extraction and bending stability for SnO2 ETL. Moreover, the internal stress of perovskite films is also reduced. As a result, SnO2/Y6‐based FPSCs achieved a power conversion efficiency (PCE) of 20.09% and retained over 80% of their initial efficiency after 1000 bending cycles at a curvature radius of 8 mm, while SnO2‐based devices only retain 60% of their initial PCE (18.60%) upon the same bending cycles. In addition, the interfacial charge extraction is also effectively improved in conjunction with reduced defect density upon incorporation of Y6 on the SnO2 ETL, as revealed by femtosecond transient absorption (Fs‐TA) measurements.

Quasi-2D halide perovskites are good candidates for efficient and stable solar cells but they suffer from high open-circuit voltage (V oc) deficit. Here He et al. show that homogeneous energy landscape of the charge transport levels is important to suppressing the recombination and increasing V oc.

Besides device operational stability, the color stability is also an important challenge for the perovskite light-emitting diodes, especially the blue ones. Here Jiang et al. report the most efficient and color stable pure-blue perovskite LEDs so far, with a half-lifetime of 14.5 minutes.

CsPbBr3 has attracted great attention due to unique optical properties. The understanding of the multiexciton process is crucial for improving the performance of the photoelectric devices based on CsPbBr3 nanocrystals. In this paper, the ultrafast dynamics of CsPbBr3 nanocrystals is investigated by using femtosecond transient absorption spectroscopy. It is found that Auger recombination lifetime increases with the decrease of the excitation intensity, while the trend is opposite for the hot-exciton cooling time. The time of the hot-carriers cooling to the band edge is increased when the excitation energy is increased from 2.82 eV (440 nm) to 3.82 eV (325 nm). The lifetime of the Auger recombination reaches the value of 126 ps with the excitation wavelength of 440 nm. The recombination lifetime of the single exciton is about 7 ns in CsPbBr3 nanocrystals determined by nanosecond time-resolved photoluminescence spectroscopy. The exciton binding energy is 44 meV for CsPbBr3 nanocrystals measured by the temperature-dependent steady-state photoluminescence spectroscopy. These findings provide a favorable insight into applications such as solar cells and light-emitting devices based on CsPbBr3 nanocrystals.

Background: Lipocalin 2 (LCN2), a protein primarily produced by hepatocytes, is highly upregulated under various conditions that induce cellular stress, such as intoxication, infection or inflammation. However, the precise biological functions and underlying mechanisms of LCN2 in hepatocytes remains unknown. Methods: Hepatocyte stress was successfully induced by treating Huh7 cells with interleukin-1β (IL-1β). Interleukin-6 (IL-6), Tumor Necrosis Factor-α (TNF-α) and LCN2 levels were measured in IL-1β treated Huh7 cells and supernatant. Additionally, microarray analysis was conducted to identify genes differentially expressed in LCN2-silenced and control Huh7 cells. Results: TNF-α, IL-6 and LCN2 were significantly elevated in Huh7 cells after IL-1β) treatment. In LCN2-silenced Huh7 cells, expression of IL-6 and TNF-α was significantly increased when compared with the expression levels of control Huh7 cells. Furthermore, differentially expressed genes were observed between the LCN2-silenced and control cells. Microarray analysis indicated that LCN2 acted by influencing genes involved in protein metabolism, stress response, cell cycle and proliferation. Conclusions: Our results suggest that LCN2 upregulation protects hepatocytes from IL-1β-induced stress. Additionally, our microarray analysis of LCN2-silenced and control cells provides a better understanding of the mechanisms that may be influenced by LCN2 induction.