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We proposed a compliant leg configuration that enhances the conventional pantograph design with leaf springs. The following facts characterize the proposed configuration: (1) Due to the use of the pantograph structure, the mass is centralized around the hip joint, reducing the lower leg inertia; (2) Leaf springs are chosen as elastic parts to increase energy efficiency and estimate foot-end contact forces. Compared with coil springs, leaf springs require no guide rails to deploy, and their stiffness can be easily adjusted through shape cutting. Analytical models are introduced to analyze the leg's stiffness and estimate the contact forces only with the deflections of leaf springs. A one-leg robot based on the proposed design is built, and various experiments are conducted. Experiments regarding the stiffness calibration and the contact forces estimation showed an acceptable agreement with the analytical model. Experiments of dropping demonstrate the feasibility of the leg to perform spring-like behaviors. Experiments of periodic hopping demonstrate the feasibility of using spring deflections to detect touch-down events. For energy efficiency, it is also observed that the elastic leg has a 20% increment concerning the jumping height in the flight phase, compared with the one where leaf springs are replaced with rigid materials. [ABSTRACT FROM AUTHOR]

All-inorganic perovskite solar cells (PSCs) are attracting considerable attention due to their promising thermal stability, but their inferior power-conversion efficiencies (PCE) hinder their realistic application. Here, we propose an approach through surface modification based on methyl ammonium halide (MAX) for inorganic CsPbI2Br solar cells processed at a low temperature. The combined benefits of the introduced MAX modifier enable the boosting of the power conversion efficiency to 14.8% with an impressive FF of 82.2% in CsPbI2Br PSCs. Our experimental analyses coupled with optical modeling indicate that the incorporated MAX leads to an effective passivation of the surface traps originating from Pb2+ and I− ions in CsPbI2Br and simultaneously mediates the crystallization of CsPbI2Br with slightly enlarged grains and reduced numbers of structural defects and pinhole. As a result, the interfacial trap-assisted recombination is suppressed and the charge extraction is promoted. Mechanistically, we show that in the presence of MAX, the deep-level traps in the perovskites are passivated, leaving the energy of the trapping centers to become shallower. In this situation, the negative impacts of the traps on carrier transport and recombination are mitigated. [ABSTRACT FROM AUTHOR]

All-inorganic perovskite solar cells (PSCs) are attracting considerable attention due to their promising thermal stability, but their inferior power-conversion efficiencies (PCE) hinder their realistic application. Here, we propose an approach through surface modification based on methyl ammonium halide (MAX) for inorganic CsPbI2Br solar cells processed at a low temperature. The combined benefits of the introduced MAX modifier enable the boosting of the power conversion efficiency to 14.8% with an impressive FF of 82.2% in CsPbI2Br PSCs. Our experimental analyses coupled with optical modeling indicate that the incorporated MAX leads to an effective passivation of the surface traps originating from Pb2+ and I- ions in CsPbI2Br and simultaneously mediates the crystallization of CsPbI2Br with slightly enlarged grains and reduced numbers of structural defects and pinhole. As a result, the interfacial trap-assisted recombination is suppressed and the charge extraction is promoted. Mechanistically, we show that in the presence of MAX, the deep-level traps in the perovskites are passivated, leaving the energy of the trapping centers to become shallower. In this situation, the negative impacts of the traps on carrier transport and recombination are mitigated.