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Nickel oxide (NiOx) is a promising hole-selective contact to produce efficient inverted p-i-n structured perovskite solar cells (PSCs) due to its high carrier mobility and high transparency. However, the light-induced degradation of the NiOx–perovskite heterojunction is the main factor limiting its long-term operational lifetime. In this study, we used the time-resolved mass spectrometry technique to clarify the degradation mechanism of the NiOx-formamidinium–methylammonium iodide perovskite (a common composition for high-performance PSCs) heterojunction under operational conditions, and observed that (1) oxidation of iodide and generation of free protons under 1-sun illumination, (2) formation of volatile hydrogen cyanide, methyliodide, and ammonia at elevated temperatures, and (3) a condensation reaction between the organic components under a high vapor pressure. To eliminate these multi-step photochemical reactions, we constructed an aprotic trimethylsulfonium bromide (TMSBr) buffer layer at the NiOx/perovskite interface, which enables excellent photo-thermal stability, a matched lattice parameter with the perovskite crystal, and robust trap-passivation ability. Inverted PSCs stabilized with the TMSBr buffer layer reached the maximum efficiency of 22.1% and retained 82.8% of the initial value after continuous operation for 2000 hours under AM1.5G light illumination, which translates into a T80 lifetime of 2310 hours that is among the highest operational lifetimes for NiOx-based PSCs., source:https://pubs.rsc.org/en/content/articlelanding/2022/ee/d2ee01801b

Metal halide perovskite solar cells are an emerging photovoltaic technology already exhibiting great potential. The main challenges at present that hinder the application of perovskite solar cells include scalable fabrication, operational stability, and environmental impact of Pb in Pb-containing perovskite solar cells. Among various scalable coating techniques, modified chemical vapor deposition (CVD) is a promising technology to enable large-area and uniform coating of perovskite layers at a low cost. Modified CVD also offers many other advantages such as being solvent-free, high compatibility with industrial manufacturing, and easy integration with other solar technologies to form tandem cells (or perovskite–perovskite tandem cells). In this review, we present the recent development of perovskite solar cells and modules prepared by modified CVD. We first discuss the differences between modified CVD and solution coating processing. We then summarize the present results from the cost-performance analysis point of view to show the potential of modified CVD for scalable fabrication of perovskite solar cells and modules with low cost. At the end of this review, we outline several future research directions., source:https://pubs.rsc.org/en/content/articlelanding/2021/TA/D1TA06459B

The rapid development of perovskite solar cells (PSCs) in view of efficiency during the past decade has made this emerging photovoltaic (PV) technology a promising competitor in the PV market. In the next step, PSCs need be manufactured into module scale to meet the commercialization requirements for further practical application. Demonstrations of perovskite solar modules (PSMs) and their improvements in efficiency and stability have recently become an intense area of research activities. Minimodules with the size suitable for laboratory investigation are naturally recognized as a desirable model for the study of PSMs. Herein, the recent progress and challenges in perovskite solar minimodules and the efforts to improve their scalable fabrication, efficiency, and stability are reviewed. Minimodule architectures, minimodule fabrication, and progress in the scalable deposition of perovskite and charge-transport layers as well as minimodule encapsulation are also discussed., source:https://onlinelibrary.wiley.com/doi/10.1002/solr.202100458

Perovskite solar cells have emerged as one of the most promising thin-film photovoltaic (PV) technologies and have made a strong debut in the PV field. However, they still face difficulties with up-scaling to module-level devices and long-term stability issue. Here, we report the use of a room-temperature nonvolatile Lewis base additive, diphenyl sulfoxide(DPSO), in formamidinium-cesium (FACs) perovskite precursor solution to enhance the nucleation barrier and stabilize the wet precursor film for the scalable fabrication of uniform, large-area FACs perovskite films. With a parallel-interconnected module design, the resultant solar module realized a certified quasi-stabilized efficiency of 16.63% with an active area of 20.77 cm². The encapsulated modules maintained 97 and 95% of their initial efficiencies after 10,000 and 1187 hours under day/night cycling and 1-sun equivalent white-light light-emitting diode array illumination with maximum power point tracking at 50°C, respectively., source:https://www.science.org/doi/10.1126/sciadv.abg3749

The spectral instability issue is a challenge in blue perovskite light-emitting diodes (PeLEDs). Dion–Jacobson (DJ) phase perovskites are promising alternatives to achieve high-quality blue PeLEDs. However, the current exploration of DJ phase perovskites is focused on symmetric divalent cations, and the corresponding efficiency of blue PeLEDs is still inferior to that of green and red ones. In this work, we report a new type of DJ phase CsPb(Br/Cl)3 perovskite via introduction of an asymmetric molecular configuration as the organic spacer cation in perovskites. The primary and tertiary ammonium groups on the asymmetric cations bridge with the lead halide octahedra forming the DJ phase structures. Stable photoluminescence spectra were demonstrated in perovskite films owing to the suppressed halide segregation. Meanwhile, the radiative recombination efficiency of charges is improved significantly as a result of the confinement effects and passivation of charge traps. Finally, we achieved an external quantum efficiency of 2.65% in blue PeLEDs with stable spectra emission under applied bias voltages. To our best knowledge, this is the first report of asymmetric cations used in PeLEDs, which provides a facile solution to the halide segregation issue in PeLEDs., source:https://pubs.acs.org/doi/10.1021/jacs.1c07757

Lead-free tin perovskite solar cells (PSCs) have undergone rapid development in recent years and are regarded as a promising eco-friendly photovoltaic technology. However, a strategy to suppress charge recombination via a built-in electric field inside a tin perovskite crystal is still lacking. In the present study, a formamidinium tin iodide (FASnI3) perovskite absorber with a vertical Sn2+ gradient was fabricated using a Lewis base-assisted recrystallization method to enhance the built-in electric field and minimize the bulk recombination loss inside the tin perovskites. Depth-dependent X-ray photoelectron spectroscopy revealed that the Fermi level upshifts with an increase in Sn2+ content from the bottom to the top in this heterogeneous FASnI3 film, which generates an additional electric field to prevent the trapping of photo-induced electrons and holes. Consequently, the Sn2+-gradient FASnI3 absorber exhibits a promising efficiency of 13.82% for inverted tin PSCs with an open-circuit voltage increase of 130 mV, and the optimized cell maintains over 13% efficiency after continuous operation under 1-sun illumination for 1,000 h., source:https://link.springer.com/article/10.1007/s40820-022-00842-4

Polycrystalline properties of perovskites can induce the growth of different nanostructures, thanks to their facile fabrication. In this work, the CsPb2Br5 perovskite grains were used as templates to induce the growth of the ring-like structures on a SiO2/Si substrate. Owing to the oxidation of the volatile PbBr2 originated from the decomposition of CsPb2Br5, the grain boundaries of perovskites are prone to reaction with SiO2, which leads to the formation of Pb-silicate glass at high temperatures. The quasi-circular grain structure of CsPb2Br5 defines the final dimension of the Pb-silicate glass ring-like structures. X-ray photoelectron spectroscopy (XPS) measurement results reveal the formation and composition of the Pb-silicate glass ring-like structures converting from the halide perovskite film on the SiO2/Si substrate. Furthermore, these ring-like structures can extend to the field of display and pulsed-laser by combining existing techniques., source:https://aip.scitation.org/doi/abs/10.1063/5.0085137

Lithium metal batteries are promising candidates for meeting the increasing demand for next-generation energy storage devices with high energy density; however, the problems of lithium dendrites and unstable solid electrolyte interphases (SEIs) for lithium anodes with nonaqueous electrolytes severely hinder their practical applications. The first step to address these issues is to establish a better understanding about these phenomena. In this review, we first discuss the formation processes and related mechanisms of dendritic lithium and SEIs, which are revealed and supported by the specially designed setups combined with various advanced characterization techniques including operando scanning transmission electron microscopy (STEM) and deduced theoretical models. Because of the high sensitivity of lithium metal anodes to the ambient environment, their microscopic characterization remained challenging until the development of noninvasive cryogenic electron microscopy. Then, we present the real-state atomic structures and chemical compositions of lithium dendrites and SEIs by cryogenic transmission electron microscopy (cryo-TEM) coupled with electron energy loss spectroscopy (EELS). Based on these fundamental insights, various strategies including electrolyte engineering, construction of artificial SEI layers, and use of three-dimensional hosts for lithium, introduced to solve the lithium anode problems, are summarized. Finally, the future directions and opportunities regarding lithium anode research are discussed., source:https://pubs.rsc.org/en/content/articlelanding/2022/SE/D1SE01739J

Cesium lead iodide (CsPbI3) perovskite has gained great attention in the photovoltaic (PV) community because of its unique optoelectronic properties, good chemical stability and appropriate bandgap for sunlight harvesting applications. However, compared to solar cells fabricated from organic-inorganic hybrid perovskites, the commercialization of devices based on all-inorganic CsPbI3 perovskites still faces many challenges regarding PV performance and long-term stability. In this work, we discovered that tetrabutylammonium bromide (TBABr) post-treatment to CsPbI3 perovskite films could achieve synergistic stabilization with both TBA+ cation intercalation and Br-doping. Such TBA+ cation intercalation leads to one-dimensional capping with TBAPbI3 perovskite formed in situ, while the Br-induced crystal secondary growth helps effectively passivate the defects of CsPbI3 perovskite, thus enhancing the stability. In addition, the incorporation of TBABr can improve energy-level alignment and reduce interfacial charge recombination loss for better device performance. Finally, the highly stable TBABr-treated CsPbI3-based perovskite solar cells show reproducible photovoltaic performance with a champion efficiency up to 19.04%, while retaining 90% of the initial efficiency after 500 h storage without encapsulation., source:https://www.sciencedirect.com/science/article/pii/S2095495621006811

Metal halide perovskite solar cells have made significant breakthroughs in power conversion efficiency and operational stability in the last decade, thanks to the advancement of perovskite deposition methods. Solution-based methods have been intensively investigated and deliver record efficiencies. On the other hand, vapor deposition-based and assisted methods were less studied in the early years but have received more attention recently due to their great potential toward large-area solar module manufacturing and high batch-to-batch reproducibility. In addition, an in-depth understanding of perovskite crystallization kinetics during the vapor deposition based and assisted process allows increasing perovskite deposition rate and enhancing perovskite quality. In this review, the advances in vapor-based and assisted methods for the fabrication of perovskite solar cells are introduced. The quality of the perovskite layers (i.e., morphology, crystallinity, defect chemistry, carrier lifetime) fabricated by different methods is compared. The limitations of state-of-the-art vapor-deposited perovskite layers are discussed. Finally, insights into the engineering of vapor deposition based and assisted perovskite layers toward efficient and stable perovskite solar cells and modules are provided., source:https://aip.scitation.org/doi/full/10.1063/5.0085221

Flexible perovskite solar cells (F-PSCs) hold promise for portable power sources for applications in various fields, such as wearable and portable electronics and lightweight power supply in stratosphere and space applications. To date, it is still a challenge to achieve efficient and stable F-PSCs. Herein, a pre-applied strain on a flexible substrate to release the residual strain of the perovskite layers of the F-PSCs is reported. As a result, the F-PSC based on this strategy yielded a power conversion efficiency (PCE) of up to 18.71%, approaching that of its counterpart based on a glass substrate (20.32%). And it retained 90% of its initial PCE after 300 h under AM 1.5G light illumination with an extrapolated T80 lifetime (the time over which the device efficiency reduces to 80% of its initial value) exceeding 700 h. Furthermore, the PCE remained above 80% of its initial value even after 1500 tension-only bending cycles. The result of this work paves a possible way toward fabricating efficient and stable F-PSCs., source:https://pubs.rsc.org/en/content/articlelanding/2022/MA/D2MA00431C

Upscalable fabrication of efficient and stable perovskite solar modules is urgently needed for commercialization. Here we introduce methylammonium chloride additives in the co-solvent system of N-methyl-2-pyrrolidone/N,N-dimethylformamide to control the formation of intermediate phases during the growth of formamidinium–caesium lead triiodide perovskite films. We achieve high-quality films upon drying without the use of anti-solvent. By implementing bulk and surface passivation, champion efficiencies of 24.02% for a small-sized solar cell and 20.5% for a 5 cm × 5 cm solar mini-module on an aperture area of 22.4 cm2 (geometric fill factor ∼ 96%) are achieved by spin-coating. The fully blade-coated perovskite solar sub-module demonstrates a champion efficiency of 15.3% on an aperture area of 205 cm2. The solar mini-module exhibits impressive operational stability with a T80 lifetime of over 1,000 h at maximum power point tracking under continuous light illumination., source:https://www.nature.com/articles/s41560-022-01039-0

Cathode–electrolyte interphase (CEI) formation between the cathode and the electrolyte is a critical factor that determines the stability of lithium-ion batteries (LiBs). The CEI layer consists of various by-products (e.g., LiF, Li2CO3, ROLi, and ROCO2Li (R: alkyl group)) decomposed from redox reactions between the cathode and the electrolyte, which can lead to dramatic capacity fading and stability issues. Herein, we empirically identify the energy level band bending of a Ni-rich NMC cathode (i.e., Li(Ni0.5Mn0.3Co0.2)O2) with the visual evidence of Li+ transfer from the electrode to the CEI layer (adsorbate). Negatively charged elements tend to be present at the close surface of the cathode, while the positively charged Li+ migrates from the cathode to the CEI layer. Hence, a downward band bending could be depicted based on the work function and the energy level difference between the Fermi level (EF) and the valence band maximum (EVBM). Energy level alignment itself is likely to be the key process that leads to the active formation of unstable CEI layers on charge–discharge., source:https://pubs.rsc.org/en/content/articlelanding/2023/TA/D2TA07565B