Printable hole‐conductor‐free perovskite solar cells (PSCs) have attracted intensive research attention due to their high stability and simple manufacturing process. However, the cells have suffered severe potential loss in the absence of the hole transporting layer. The dimensionality of the perovskite absorber in the mesoporous carbon electrodes by conducting post‐treatments is reduced. The low‐dimensional perovskites possess wide‐bandgaps and form type‐II band alignment, favoring directional charge transportation and thus enhancing the device performance. For the cells using MAPbI3 (MA = methylammonium) as the light absorber, the open‐circuit voltage (VOC) is significantly enhanced from 0.92 to 0.98 V after posttreatment, delivering an overall efficiency of 16.24%. For the cells based on FAPbI3 (FA = formamadinium), a high efficiency of 17.47% is achieved with VOC of 1.02 V, which are both the highest reported values for printable hole‐conductor‐free PSCs. This strategy provides a facile method for tuning the energy level alignment for mesoscopic perovskite‐based optoelectronics.

Formamidinium lead triiodide (FAPbI3) perovskite has attracted intensive research attention due to its ideal band gap and low defect density for photovoltaic applications. Particularly, the existence of non-photoactive δ-phase FAPbI3 has been considered detrimental to regular-structured perovskite solar cells (PSCs). Here, in hole-conductor-free triple-mesoscopic PSCs, we observe that α-phase FAPbI3 transforms to δ-phase FAPbI3 at the perovskite/carbon interface and in situ forms an α/δ-phase junction when the as-fabricated cells are exposed to humid atmosphere. The α/δ-phase junction shows a favorable band alignment and significantly suppresses the charge recombination at the interface. By controlling the relative humidity of the atmosphere, we fabricate FAPbI3-based cells that deliver a champion efficiency of 17.11% with an enhanced open-circuit voltage (V OC) of 1020 mV. This work demonstrates the potential of δ-phase FAPbI3 for benefiting the device performance of PSCs and proposes the concept of constructing perovskite-based junctions at the interface between a perovskite-absorbing layer and charge-transporting layers for enhancing the V OC of PSCs.

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Doping bismuth ions in the lattice of ceria was found to be an effective method for improvement of the catalytic performance. Herein, a series of Ce x Bi1–x O y (x = 0, 0.25, 0.5, and 0.75) catalysts was synthesized by the reverse coprecipitation method, and their catalytic activities were evaluated at both loose and tight contact modes. It was found that doping of Bi in the CeO2 lattice significantly improved the mobility of lattice oxygen in Ce x Bi1–x O y catalysts, and Ce0.5Bi0.5O y demonstrated the best catalytic performance, especially at loose contact mode. The activation energy of soot combustion for Ce0.5Bi0.5O y was determined to be 133 kJ mol–1. The impact of Bi doping on the low-temperature activity of Ce x Bi1–x O y catalysts was also examined. It was found that the lattice oxygen of unstable Bi–O–Ce species was easier to transfer to the catalyst surface and react with soot at high temperatures. The cyclic tests of catalysts demonstrated that Ce0.5Bi0.5O y could maintain a decent thermal stability. Overall, this study discovered the importance of lattice oxygen in soot combustion for the doped catalysts, which is of great significance for their future applications.

Perovskite solar cells (PSCs) have achieved high efficiencies with diversified device architectures. In particular, printable mesoscopic PSC has attracted intensive research attention due to its simple fabrication process and superior stability. However, in the absence of hole conductors, the unfavorable energy band alignment between the perovskite and the carbon electrode usually leads to the reduction of device performance, especially the open-circuit voltage (V OC ). Here, a p-type molecule, 2,3,5,6tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), is utilized to post-treat the perovskite/carbon interface, which benefits the charge transfer and suppresses the charge recombination within the device. As a result, the post-treated device delivers a power conversion efficiency of 18.05% with an enhanced V OC of 1044 mV. This work provides a facile method for tuning the interfacial energy band alignment and improving performance of printable mesoscopic PSCs.

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The anion exchange between MAPbX3 (X = I- or Br-) and MAX salts in solution environment is investigated. We find I- can enter MAPbBr3 single crystals (SC) in millimeter scale,...

We propose and numerically demonstrate a scheme for physical-layer security based on chaotic phase encryption, where the transmitted carrier signal is used as the common injection for chaos synchronization, so there is no need for additional common driving. To ensure privacy, two identical optical scramblers consisting of a semiconductor laser and a dispersion component are used to observe the carrier signal. The results show that the responses of the optical scramblers are highly synchronized but are not synchronized with the injection. By properly setting the phase encryption index, the original message can be well encrypted and decrypted. Moreover, the legal decryption performance is sensitive to the parameter mismatch, since it can degrade the synchronization quality. A slight drop in synchronization induces an evident deterioration in decryption performance. Therefore, without perfectly reconstructing the optical scrambler, the original message cannot be decoded by an eavesdropper.