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Perovskite photovoltaics are gaining increasing common ground to partner with or compete with silicon photovoltaics to reduce cost of solar energy. However, a cost-effective waste management for toxic lead (Pb), which might determine the fate of this technology, has not been developed yet. Here, we report an end-of-life material management for perovskite solar modules to recycle toxic lead and valuable transparent conductors to protect the environment and create dramatic economic benefits from recycled materials. Lead is separated from decommissioned modules by weakly acidic cation exchange resin, which could be released as soluble Pb(NO 3 ) 2 followed by precipitation as PbI 2 for reuse, with a recycling efficiency of 99.2%. Thermal delamination disassembles the encapsulated modules with intact transparent conductors and cover glasses. The refabricated devices based on recycled lead iodide and recycled transparent conductors show comparable performance as devices based on fresh raw materials. Cost analysis shows this recycling technology is economically attractive. Perovskite photovoltaics has become more competitive against silicon counterpart in reducing cost of solar energy, yet the management of toxic lead hampers it application. Here, the authors propose a cost-effective environmental-friendly approach to recycle lead and transparent conductors.

The efficiency and stability of perovskite solar cells are essentially determined by defects in the perovskite layer, yet their chemical nature and linking with the degradation mechanism of devices remain unclear. Here we uncover where degradation occurs and the underlying mechanisms and defects involved in the performance degradation of p–i–n perovskite solar cells under illumination or reverse bias. Light-induced degradation starts with the generation of iodide interstitials at the interfacial region between the perovskite and both charge transport layers. While we observe trap annihilation of two types of iodide defect at the anode side, we find negatively charged iodide interstitials near the cathode side, which we show to be more detrimental to the solar cell efficiency. The reverse-bias degradation is initialized by the interaction between iodide interstitials and injected holes at the interface between the electron transport layer and the perovskite. Introducing a hole-blocking layer between the layers suppresses this interaction, improving the reverse-bias stability. The efficiency of perovskite solar cells decreases over time, yet the underlying mechanisms are unclear. Ni et al. observe charged iodide interstitial defects within the device layers and how they contribute to the efficiency degradation when the cell is operated under illumination or reverse bias.

One major concern for the commercialization of perovskite photovoltaic technology is the toxicity of lead from the water-soluble lead halide perovskites that can contaminate the environment. Here, we report an abundant, low-cost and chemically robust cation-exchange resin (CER)-based method that can prevent lead leakage from damaged perovskite solar modules under severe weather conditions. CERs exhibit both high adsorption capacity and high adsorption rate of lead in water due to the high binding energy with lead ions in the mesoporous structure. Integrating CERs with carbon electrodes and layering them on the glass surface of modules has a negligible detrimental effect on device efficiency while reducing lead leakage from perovskite mini-modules by 62-fold to 14.3 ppb in water. The simulated lead leakage from damaged large-area perovskite solar panels treated with CERs can be further reduced to below 7.0 ppb even in the worst-case scenario that every sub-module is damaged. Lead leakage from damaged perovskite photovoltaic modules poses health and environmental risks limiting the potential use of the technology. Now Chen et al. show that the encapsulation of perovskite modules with a cation-exchange resins reduces lead leakage to 14.3 ppb in waste water.

Interstitial iodides are the most critical type of defects in perovskite solar cells that limits efficiency and stability. They can be generated during solution, film, and device processing, further accelerating degradation. Herein, we find that introducing a small amount of a zinc salt- zinc trifluoromethane sulfonate (Zn(OOSCF 3 ) 2 ) in the perovskite solution can control the iodide defects in resultant perovskites ink and films. CF 3 SOO ̶ vigorously suppresses molecular iodine formation in the perovskites by reducing it to iodide. At the same time, zinc cations can precipitate excess iodide by forming a Zn-Amine complex so that the iodide interstitials in the resultant perovskite films can be suppressed. The perovskite films using these additives show improved photoluminescence quantum efficiency and reduce deep trap density, despite zinc cations reducing the perovskite grain size and iodide interstitials. The zinc additives facilitate the formation of more uniform perovskite films on large-area substrates (78-108 cm 2 ) in the blade-coating process. Fabricated minimodules show power conversion efficiencies of 19.60% and 19.21% with aperture areas of 84 and 108 cm 2 , respectively, as certified by National Renewable Energy Laboratory (NREL), the highest efficiency certified for minimodules of these sizes. Interstitial iodides are the most critical type of defects in perovskite solar cells that limits efficiency and stability. Here, the authors introduce small amount of zinc trifluoromethane sulfonate to control iodide defects, facilitating fabrication of minimodules with efficiencies of over 19%.

In the era of information explosion, the energy consumption of cloud data centers is significant. It’s critical to reduce the energy consumption of large-scale data centers while guaranteeing quality of service (QoS), especially the energy consumption of video cloud computing platforms. The application of virtual machine (VM) consolidation has been regarded as a promising approach to improve resource utilization and save energy of the data centers. In this paper, an energy efficient and QoS-aware VM consolidation method is proposed to address the issues. A combined prediction model based on grey model and ARIMA is applied to host status detection, and we provide a new scheme that VM placement policy based on resource utilization and varying energy consumption to search most suitable host and VM selection policy called AUMT selecting VM with low average CPU utilization and migration time. Extensive experimental results based on the cloudsim simulator demonstrate that proposed approach enables to achieve the objectives reducing energy consumption, number of migrations, SLAV and ESV by an average of 56.07%, 79.21%, 91.01% and 84.34% compared with the benchmark methods and the AUMT can reduce energy consumption, the number of migrations and ESV by an average of 15.46%, 28.11% and 3.96% compared with the state-of-the-art method.

Perovskite/silicon tandem solar cells can exceed Shockley-Queisser limit, but achieving complete coverage of 2-4 μm pyramids on industrial fully-textured silicon with solution-processed perovskite film remains challenging. We address this issue by spray-coating alumina particles onto fully-textured silicon, creating a super-hydrophilic rough surface that both enhances wet film coverage and provides guided nucleation sites. Although super-hydrophilic effect enhances wetting, it alone is insufficient to achieve complete coverage of pyramids by perovskite film. Beyond enhanced wetting, alumina particles promote uniform nucleation at particle-decorated sites across pyramids by lowering nucleation barrier and suppressing valley-preferred nucleation, which enables near-conformal deposition of perovskite film on pyramids. Additionally, alumina particles reduce nonradiative recombination and extend carrier lifetimes. Using this approach, we achieve a efficiency of 32.74% for perovskite/silicon tandem solar cells with one-step solution-processed perovskite on fully-textured silicon. This strategy offers a pathway for seamless integration of perovskite and silicon photovoltaics into high-performance tandem devices. Achieving complete coverage of 2-4 μm pyramids on industrial fully-textured silicon with solution processed perovskite film remains challenging. Here, authors spray-coat alumina particles on silicon for near-conformal deposition of perovskites, achieving efficiency of 32.74% for tandem solar cells.

The efficiency and stability of bifacial perovskite solar modules are still relatively low. Here we report bifacial minimodules with front efficiency comparable to opaque monofacial counterparts, while gaining additional energy from albedo light. We add a hydrophobic additive to the hole transport layer to protect the perovskite films from moisture. We integrate silica nanoparticles with proper size and spacing in perovskite films to recover the absorption loss induced by the absence of reflective metal electrodes. The small-area single-junction bifacial perovskite cells have a power-generation density of 26.4 mW cm −2 under 1 sun illumination and an albedo of 0.2. The bifacial minimodules show front efficiency of over 20% and bifaciality of 74.3% and thus a power-generation density of over 23 mW cm −2 at an albedo of 0.2. The bifacial minimodule retains 97% of its initial efficiency after light soaking under 1 sun for over 6,000 hours at 60 ± 5 °C. The performance of perovskite bifacial modules is still relatively poor. Now Gu et al. optimize the design of minimodules and achieve a power density of 23 mW cm − 2 at an albedo of 0.2 and operational stability of 6,000 h.

Objectives To present a new method consisting of cable cerclage and hook plate for fixating the comminuted inferior patellar pole fracture and evaluate the outcomes. Methods A total of 16 consecutive patients who were treated with the construct of a cable cerclage in combination with a hook plate between January 2018 and September 2020 were included in the study. Mechanism of injury, duration, and technical details of the operation were reviewed. Plain radiographs and computerized tomography (CT) scans were routinely taken to evaluate the fracture pattern. The primary outcome measures included bony healing time, pain intensity‐numerical rating scale (PI‐NRS), range of motion (ROM), and the Bostman score at the final follow‐up. Results Eight males and eight females with an average age of 55.6 ± 12.0 years (range, 41 to 73 years) were included. Bony union was achieved in all the patients, with an average healing time of 10.8 ± 2.4 weeks (range, 8–16 weeks). With the average follow‐up of 20.1 ± 5.3 months, 12 patients (75%) had no pain (PI‐NRS score of 0), and the remaining four patients (25%) reported mild pain (three with a PI‐NRS score of 1 and one with a score of 2). The final Bostman score was 27.8 ± 3.0 (range, 20–30) on average, and all the patients showed excellent or good results. The average range of motion was 127.5° ± 13.9° (range, 90°–140°). No implant failure or hardware irritation was found during the follow‐up. Conclusion The fixation of cable cerclage combined with hook plate resulted as a reliable method for managing the inferior patellar pole fractures, allowing immediate rehabilitation and weight‐bearing.

Virtual machine scheduling and resource allocation mechanism in the process of dynamic virtual machine consolidation is a promising access to alleviate the cloud data centers of prominent energy consumption and service level agreement violations with improvement in quality of service (QoS). In this article, we propose an efficient algorithm (AESVMP) based on the Analytic Hierarchy Process (AHP) for the virtual machine scheduling in accordance with the measure. Firstly, we take into consideration three key criteria including the host of power consumption, available resource and resource allocation balance ratio, in which the ratio can be calculated by the balance value between overall three-dimensional resource (CPU, RAM, BW) flat surface and resource allocation flat surface (when new migrated virtual machine (VM) consumed the targeted host’s resource). Then, virtual machine placement decision is determined by the application of multi-criteria decision making techniques AHP embedded with the above-mentioned three criteria. Extensive experimental results based on the CloudSim emulator using 10 PlanetLab workloads demonstrate that the proposed approach can reduce the cloud data center of number of migration, service level agreement violation (SLAV), aggregate indicators of energy comsumption (ESV) by an average of 51.76%, 67.4%, 67.6% compared with the cutting-edge method LBVMP, which validates the effectiveness.