Dominant non-local superconducting proximity effect due to electron-electron interaction in a ballistic double nanowire

Cooper pair splitting (CPS) can induce non-local correlation between two normal conductors coupling to a superconductor. CPS into a double one-dimensional electron gas is an appropriate platform for extracting large amount of entangled electron pairs and one of the key ingredients for engineering Majorana Fermions with no magnetic field. Here we study CPS using a Josephson junction of a gate-tunable ballistic InAs double nanowire. The measured switching current into the two nanowires significantly larger than sum of that into the respective nanowires, indicating the inter-wire superconductivity dominant compared to the intra-wire superconductivity. From dependence on the number of propagating channels in the nanowires, the observed CPS is assigned to one-dimensional electron-electron interaction. Our results will pave the way for utilizing one-dimensional electron-electron interaction to reveal physics of high-efficient CPS and engineer Majorana Fermions in double nanowire systems via CPS

Niobium Incorporation into CsPbI2Br for Stable and Efficient All-Inorganic Perovskite Solar Cells

All-inorganic perovskites are attracting increasing attention due to their superior thermal stability than that of the traditional CH3NH3PbI3, while their inferior phase stability in ambient conditions is still an unsolved issue. Here, for the first time, we report the incorporation of niobium (Nb5+) ions into the CsPbI2Br perovskite. Results indicate that Nb5+ can effectively stabilize the photoactive α-CsPbI2Br phase by the possible substitution of Pb2+. With 0.5% Nb doping, the carbon electrode-based all-inorganic perovskite solar cells achieved a high photoconversion efficiency value of 10.42%, 15% higher than that of the control device. The Nb5+ incorporation reduces the charge recombination in the perovskite, leading to a champion Voc value of 1.27 V and a negligible hysteresis effect. This work explicates the high compatibility of all-inorganic perovskite materials and unlocks the opportunities for the use of high-valence ions for perovskite property modification

Field angle dependence of the zero-energy density of states in unconventional superconductors: analysis of the borocarbide superconductor YNi2B2C

We investigate the field-angle-dependent zero-energy density of states for YNi2B2C with using realistic Fermi surfaces obtained by band calculations. Both the 17th and 18th bands are taken into account. For calculating the oscillating density of states, we adopt the Kramer-Pesch approximation, which is found to improve accuracy in the oscillation amplitude. We show that superconducting gap structure determined by analyzing STM experiments is consistent with thermal transport and heat capacity measurements.Comment: 4 pages, 1 figure, 25th international conference on Low Temperature Physics (Amsterdam, The Netherlands, August 6-13 2008) LT1597, to be published in Journal of Physics: Conference Series 200

Achievable high Voc of carbon based all-inorganic CsPbIBr2 perovskite solar cells through interface engineering

In this work, a simple interface engineering process for SnO2 electron selective layer (ESL) surface passivation employing a SnCl2 solution is introduced, which has successfully reduced the energy loss for a high open-circuit voltage (Voc) output and consequently improved the performance of all-inorganic CsPbIBr2 perovskite solar cells (PSCs). It was found that surface passivation can effectively suppress the recombination process at the interface between the perovskite and SnO2 due to higher recombination resistance. The shorter PL decay time is attributed to the excellent electron extraction from the perovskite film. After optimizing surface passivation, the power conversion efficiency (PCE) was enhanced from 4.73% to 7.00% and a high Voc of 1.31 V was achieved, which is one of the highest Voc values reported for inorganic Cs-based PSCs. More importantly, the passivated SnO2 based device retains 95.5% of its initial performance at 90 °C in air without encapsulation. This work provides a simple and efficient interface engineering method to improve the Voc and efficiency of all-inorganic PSCs

The Role of Lanthanum in a Nickel Oxide‐Based Inverted Perovskite Solar Cell for Efficiency and Stability Improvement

A high‐performing inverted perovskite solar cell (PSC) always relies on the hole transporting layer (HTL) quality and its interfaces. This work investigates the impact of La incorporation within the NiOx matrix for defects passivation, thus leading to high charge extraction ability and stability without compromising its power conversion efficiency. In the presence of La, the La–NiOx quality is clearly improved; without the formation of pinholes. In addition, the inclusion of La alters the energy band alignment; consequently, enhancing the hole transportation and widening the Voc (>1 V), as compared to the pristine NiOx. The beneficial effect of La was further revealed through the photoluminescence measurement and density of states (DOS) analysis, in which trap states are passivated by La. More importantly, the perovskite solar cell, with La–NiOx as the HTL, exhibits 21% enhancement in efficiency and a remarkable stability that is greater than that of pristine NiOx. This also unlocks an opportunity for commercialization

Development of a Mixed Halide-chalcogenide Bismuth-based Perovskite MABiI2S with Small Bandgap and Wide Absorption Range

During the last years, lead perovskites have achieved high power conversion efficiency of 23%. However, their long-term stability and toxicity are still crucial issues that required attention. In this study, we are the first to report on the synthesis and characterizations of a new lead-free mixed halide-chalcogenide perovskite MABiI2S (MBIS), and have determined its physical and optical properties by various testing methods. The MBIS has a low bandgap of 1.52 eV, with an extended absorption onset up to over 1000 nm. Solar cells fabricated with the MBIS were inspected and device improvements were applied

La-doped SnO2 as ETL for efficient planar-structure hybrid perovskite solar cells

SnO2 has attracted considerable attention in perovskite solar cells (PSCs) due to its excellent optical and electrical properties. However, a poor surface morphology, specifically with the presence of pinholes after the annealing process, limits its application in PSCs. To overcome the drawback of tin oxide, lanthanum (La) is herein first to be doped into the SnO2 layer, which is able to alleviate the SnO2 crystal aggregation and produce full-coverage and a uniform film. In addition, La:SnO2 can effectively reduce the band offset of the SnO2 layer, which results in the high Voc of 1.11 V. Systematic analyses revealed that the La:SnO2 layer enhances the electron extraction and suppresses charge recombination, leading to the power conversion efficiency (PCE) enhancement from 14.24% to 17.08%

High Electrical Conductivity 2D MXene Serves as Additive of Perovskite for Efficient Solar Cells

MXenes, a newly intriguing family of 2D materials, have recently attracted considerable attention owing to their excellent properties such as high electrical conductivity and mobility, tunable structure, and termination groups. Here, the Ti3C2Tx MXene is incorporated into the perovskite absorber layer for the first time, which aims for efficiency enhancement. Results show that the termination groups of Ti3C2Tx can retard the crystallization rate, thereby increasing the crystal size of CH3NH3PbI3. It is found that the high electrical conductivity and mobility of MXene can accelerate the charge transfer. After optimizing the key parameters, 12% enhancement in device performance is achieved by 0.03 wt% amount of MXene additive. This work unlocks opportunities for the use of MXene as potential materials in perovskite solar cell applications