Minimizing Voltage Losses via Synergistically Reducing Hetero-Interface Energy Offset for High Efficiency Perovskite Solar Cells.

The open circuit voltage (VOC) losses at multiple interfaces within perovskite solar cells (PSCs) limit the improvements in power conversion efficiency (PCE). Herein, a tailored strategy is proposed to reduce the energy offset at both hetero-interfaces within PSCs to decrease the VOC losses. For the interface of perovskite and electron transport layer where exists a mass of defects, it uses the pyromellitic acid to serve as a molecular bridge, which reduces non-radiative recombination and energy level offset. For the interface of perovskite and hole transport layer, which includes a passivator of PEAI, the detrimental effect (negative shift of work function) of PEAI passivation and optimizing the interface energy level alignment are neutralized by incorporating (2-(4-(bis(4-methoxyphenyl)amino)phenyl)-1-cyanovinyl)phosphonic acid. Owing to synergistically reduced hetero-interface energy offset, the PSCs achieve a PCE of 25.13%, and the VOC is increased from 1.134 to 1.174 V. In addition, the resulting PSCs possess enhanced stability, the unencapsulated PSCs can maintain ≈96% and ≈97% of their initial PCE after 2000 h of aging under ambient conditions and 210 h under operation conditions.

Cascade Reaction in Organic Hole Transport Layer Enables Efficient Perovskite Solar Cells.

The doped organic hole transport layer (HTL) is crucial for achieving high-efficiency perovskite solar cells (PSCs). However, the traditional doping strategy undergoes a time-consuming and environment-dependent oxidation process, which hinders the technology upgrades and commercialization of PSCs. Here, we reported a new strategy by introducing a cascade reaction in traditional doped Spiro-OMeTAD, which can simultaneously achieve rapid oxidation and overcome the erosion of perovskite by 4-tert-butylpyridine (tBP) in organic HTL. The ideal dopant iodobenzene diacetate was utilized as the initiator that can react with Spiro to generate Spiro⋅+ radicals quickly and efficiently without the participation of ambient air, with the byproduct of iodobenzene (DB). Then, the DB can coordinate with tBP through a halogen bond to form a tBP-DB complex, minimizing the sustained erosion from tBP to perovskite. Based on the above cascade reaction, the resulting Spiro-based PSCs have a champion PCE of 25.76 % (certificated of 25.38 %). This new oxidation process of HTL is less environment-dependent and produces PSCs with higher reproducibility. Moreover, the PTAA-based PSCs obtain a PCE of 23.76 %, demonstrating the excellent applicability of this doping strategy on organic HTL.

Oriented Molecular Bridge Constructs Homogeneous Buried Interface for Perovskite Solar Cells with Efficiency Over 25.3.

Buried interface optimization matters the efficiency improvement of planar perovskite solar cells (PSCs), and the molecular bridge is reported to be an effective approach. Herein, a molecular bridge is constructed at buried interface using 4-chloro-3-sulfamoylbenzoic acid (CSBA), and its preferred arrangement is systematically investigated. It is elucidated that the CSBA molecular is prone to be orientationally absorbed on TiO2 surface through COOH-Ti, and then connect with perovskite through S═O-Pb, resulting in a feasible oriented molecular bridge. Contributing to the passivated interfacial defects, optimized interfacial energy level, and released perovskite tensile stress, resulting from the oriented CSBA molecular bridge, the PSCs with an active area of 0.08 cm2 achieve a certified power conversion efficiency (PCE) of 25.32%, the highest among the TiO2-based planar PSCs. Encouragingly, the PSCs with an active area of 1 cm2 achieve a champion PCE of 24.20%, significantly promoting the efficiency progress of large-area PSCs. In addition, the PSCs with oriented CSBA molecular bridge possess enhanced stability, the unencapsulated PSCs can maintain ≈91% and ≈85% of their initial PCE after 3000 h aging under ambient condition and 1200 h aging under exposure to UV irradiation.

In situ surface regulation of 3D perovskite using diethylammonium iodide for highly efficient perovskite solar cells.

Surface passivation by constructing a 2D/3D structure is considered to be an effective strategy for suppressing non-radiative recombination and improving the device efficiency and stability. Herein, the 2D perovskite is formed in situ on the surface of a 3D perovskite via chemical interactions between diethylammonium iodide (DAI) and Pb-I octahedra, which greatly reduces the deep level defects and non-radiative recombination. Moreover, the 2D/3D structure can regulate the energy level alignment, enhance the charge extraction, and improve the open-circuit voltage. Finally, compared with the control device, the power conversion efficiency (PCE) of the DAI-treated device increases from 21.58 to 23.50%. The unencapsulated devices stored in air for more than 500 hours can still retain 97% of their initial PCE, revealing good long-term placement stability. This work provides a promising strategy to fabricate efficient PSCs through the in situ construction of 2D/3D perovskite heterojunctions.

An improved path planning algorithm based on artificial potential field and primal-dual neural network for surgical robot.

Safety and accuracy are essential for path planning in a surgical navigation system. In this paper, an improved path planning algorithm is proposed to increase the autonomous level of spine surgery robots for higher safety and accuracy. Firstly, the dynamic gravitational constant and piecewise repulsion function are adopted to improve the traditional Artificial Potential Field algorithm to solve the common issues of path planning, including local minimum, unable to reach the target near obstacles. To better control the pose of the end-effector in an operation space, the positions of the two endpoints of the end-effector are further constrained. Secondly, an improved Primal-Dual Neural Network with multiple constraints is proposed to minimize the joint angular velocity norm. The multiple constraints are formulated according to the planned path, the obstacle avoidance of the robot and the joint limits. Moreover, a real-time planned velocity scheme is applied to prevent the accumulation of position errors. The simulation results of the pedicle screw implantation demonstrate that the robot can find the collision-free trajectory and arrive at the target position in various complicated situations. More specifically, the error between two endpoints of the end-effector and the target pose is below 0.1 mm in reaching the surgical tool pose, while the maximum position error is around 0.05 mm when performing the planned path. Moreover, two experiments are conducted in the real-world to verify the proposed algorithm is effective in practice.

Impact of Precursor Concentration on Perovskite Crystallization for Efficient Wide-Bandgap Solar Cells.

High-crystalline-quality wide-bandgap metal halide perovskite materials that achieve superior performance in perovskite solar cells (PSCs) have been widely explored. Precursor concentration plays a crucial role in the wide-bandgap perovskite crystallization process. Herein, we investigated the influence of precursor concentration on the morphology, crystallinity, optical property, and defect density of perovskite materials and the photoelectric performance of solar cells. We found that the precursor concentration was the key factor for accurately controlling the nucleation and crystal growth process, which determines the crystallization of perovskite materials. The precursor concentration based on Cs0.05FA0.8MA0.15Pb(I0.84Br0.16)3 perovskite was controlled from 0.8 M to 2.3 M. The perovskite grains grow larger with the increase in concentration, while the grain boundary and bulk defect decrease. After regulation and optimization, the champion PSC with the 2.0 M precursor concentration exhibits a power conversion efficiency (PCE) of 21.13%. The management of precursor concentration provides an effective way for obtaining high-crystalline-quality wide-bandgap perovskite materials and high-performance PSCs.

Discovery of Potent Glucokinase and PPARγ Dual-Target Agonists through an Innovative Scheme for Regioselective Modification of Silybin.

Glucokinase (GK) and PPARγ are important targets for antidiabetic use. Silybin is one of the major active ingredients of Silybum marianum. The regioselective modification of the five hydroxyl groups in the silybin structure has always been a challenge. In this study, we found that silybin was an agonist of GK and PPARγ. A novel synthesis scheme of silybin derivatives was designed, and a series of novel silybin derivatives has been synthesized. The derivative 8d showed relatively strong activation activity for GK and PPARγ in enzyme activity and transactivation assays (GK activation fold: 1.86; PPARγ transactivation activation percentage: 90.32%). This research suggests that silybin and its derivatives could be used as novel GK and PPARγ dual-target agonists.

Facile Method of Solvent-Flushing To Building Component Distribution within Photoactive Layers for High-Performance Organic Solar Cells.

Suitable donor and acceptor distribution in the blended photoactive layer benefits the charge transfer and exciton separation to boost the performance of organic solar cells (OSCs). Herein, we propose a universal solvent-flushing method for building component distribution in photoactive layers based on the different solubilities of the donor and acceptor in acetylacetone (Acac). The donor and acceptor concentration distribution through the photoactive layers is investigated by the time-of-flight secondary-ion mass spectroscopy, and the surface concentration changes are examined by contact angle measurements and atomic force microscopy tests. The charge-transfer properties of OSCs before and after Acac flushing are further investigated by the rectification ratio and light intensity-dependent Jsc and Voc measurements. For inverted OSCs based on PBDB-TF:IT-4F, the power conversion efficiency (PCE) enhances from 12.87 to 14.05%, and for a PBDB-TF:Y6-based device, the PCE also significantly increases from 15.40 to 16.51% because of greatly enhanced Jsc and FF, benefited from enhanced charge transport and suppressed charge recombination by solvent-flushing. Our findings suggest that solvent-flushing is a simply processed and easily controlled method to achieve vertical component distribution in photoactive layers to boost the performance of OSCs.