Carbon-based electrodes have been widely applied in perovskite solar cells (PSCs) because of their chemical inertness and compatibility with up-scalable techniques, signifying their solid potential for mass-production. The material scarcity...

This review systematically describes the origins, characterization and implications of strain in perovskite solar cells and proposes novel control strategies.

Interface engineering and passivating contacts are key enablers to reach the highest efficiencies in photovoltaic devices. While printed carbon–graphite back electrodes for hole‐transporting material (HTM)‐free perovskite solar cells (PSCs) are appealing for fast commercialization of PSCs due to low processing costs and extraordinary stability, this device architecture so far suffers from severe performance losses at the back electrode interface. Herein, a 2D perovskite passivation layer as an electron blocking layer (EBL) at this interface to substantially reduce interfacial recombination losses is introduced. The formation of the 2D perovskite EBL is confirmed through X‐ray diffraction, photoemission spectroscopy, and an advanced spectrally resolved photoluminescence microscopy mapping technique. Reduced losses that lead to an enhanced fill factor and VOC are quantified by electrochemical impedance spectroscopy and JSC–VOC measurements. This enables reaching one of the highest reported efficiencies of 18.5% for HTM‐free PSCs using 2D perovskite as an EBL with a significantly improved device stability.

Metal-halide perovskites are a class of optoelectronic materials for solar cells. Since Miyasaka et al. first reported perovskite solar cells (PSCs) based on a liquid junction in 2009, [1] recent solidstate PSCs using 3D polycrystalline perovskites have demonstrated a certified power conversion efficiency (PCE) of 25.7% being comparable to the existing photovoltaic technology of Si solar cells. [2] The achievement of the high-efficiency PSCs can be attributed to the excellent optoelectronic properties of perovskite light absorbers with a high-absorption coefficient and long-range carrier diffusion length. Also, its simple fabrication process using low-cost materials opens a bright prospect of commercialization of PSCs in the energy industry. In general, the lattice structure of metal-halide perovskites consists of three distinct positions that formulate ABX 3 cubic unit cells, where cation A (e.g., methylammonium (MA þ ), formamidinium (FA þ ), and/or Cs þ ) is located at (0,0,0), cation B (e.g., Pb 2þ ) is at (1/2,1/2,1/2), and halide X (e.g., Cl À , Br À , and I À ) is at the center of the six planes of the cubic at (1/2,1/2,0) (Figure 1a). [3] Therefore, when the Goldschmidt tolerance factor is between 0.8 and 1.0, and the octahedral factor is between 0.442 and 0.895, 3D perovskites can be formulated with a high degree of freedom in terms of compositional engineering, which has enabled and will enable the advancement of perovskites as a light absorber. [3,4] Nevertheless, perovskites fundamentally suffer from their internal defects in the bulk and at the surface of their polycrystalline film. [5][6][7][8] The presence of some defects accompanies the formation of electronic states within the bandgap of perovskites, leading to nonradiative recombination of excitons and charge carriers, thereby degrading photovoltaic characteristics of PSCs. Furthermore, the defects cause structural degradation of perovskites as they migrate due to their ionic nature. [9] Certainly, deeplevel defects are undesirable because they are primary nonradiative recombination center trapping excitons and charge carriers. In contrast, the so-called defect tolerance of perovskites, i.e., those with the benign nature of the shallow defects, has been known to enable efficient radiative recombination of charge carriers. [10] However, the shallow-level defects may also be problematic as they can lead to the formation of polarons that may activate the nonradiative process degrading the photovoltaic performance of PSCs. [11] Several studies have revealed that interstitial iodide and iodide vacancy are responsible for the formation of deep-, and shallow-level trap states, respectively, [12,13] and their high density in perovskites due to the low formation energy may result

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Abstract：Recently we have a growing interest in environmental pollution and alternative energy. Diesel engine is generally used to produce the power on the ground and the sea. However, the combustion characteristics are changed on account of the wear of fuel system and the altered ambient condition of the combustion chamber by the increment of the engine operation hour. Therefore combustion characteristics on fuel injection timing are experimentally investigated to find out the optimum fuel injection timing in the case of the aged diesel engine using biodiesel blend oil. Cylinder pressure, rate of pressure rise, rate of heat release and combustion gas temperature are risen by the advancing fuel injection timing, while the exhaust gas temperature and soot emission level are decreased by the advancing of fuel injection timing. The least specific fuel oil consumption is indicated at BTDC 26 〬 CA on the 75%load and at 1800rpm.

While perovskite photovoltaic (PV) devices are on the verge of their commercialization, promising methods to recycle or remanufacture fully-encapsulated perovskite solar cells (PSCs) and modules are still missing. Through detailed life-cycle assessment shown in this work, we identify that the majority of the greenhouse gas emissions can be reduced by re-using the glass substrate and parts of the PV cells. Based on these analytical findings, we develop a novel thermally-assisted mechanochemical approach to remove the encapsulants, the electrode and the perovskite absorber, allowing to re-use most of the device constituents for remanufacturing PSCs, which recovered nearly 90% of their initial performance. This remanufacturing strategy allows to save up to 33% of the module’s global warming potential. Finally, we demonstrate that the CO2-footprint of these remanufactured devices can become less than 30g/kWh, which is the value for state-of-the-art c-Si PV modules and can even reach 15g/kWh assuming a similar lifetime

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