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The primary stage of joint formation of silver nanowires (AgNWs) at 60 °C is investigated by using rotary scanning transmission electron microscopy (STEM with tomographic reconstruction images) and super-large-scale molecular dynamic (MD) simulation (2 × 106 atoms). This study proves to establish that silver nanowires do not require the conventional high-temperature post-treatment process at 200 °C to form fused contacts at the intersections. In fact, a low-temperature annealing at 60 °C facilitates formation of highly conductive networks. The connection between the nanowires is made through a stage called thinning, shown in this report for the first time, which occurs before broadening of the nanowires and is caused due to simultaneous effects of loads from the top nanowires and the heating, as confirmed by STEM and MD results. The outcomes of our investigation significantly promote the application of AgNWs as a transparent conductive layer for solar cells with requirement of low-temperature processing such as kasterite, perovskite, and organic solar cells. [ABSTRACT FROM AUTHOR]

Semiconductors with multiple anions currently provide a new materials platform from which improved functionality emerges, posing new challenges and opportunities in material science. This review has endeavored to emphasize the versatility of the emerging family of semiconductors consisting of mixed chalcogen and halogen anions, known as "chalcohalides". As they are multifunctional, these materials are of general interest to the wider research community, ranging from theoretical/computational scientists to experimental materials scientists. This review provides a comprehensive overview of the development of emerging Bi- and Sb-based as well as a new Cu, Sn, Pb, Ag, and hybrid organic-inorganic perovskite-based chalcohalides. We first highlight the high-throughput computational techniques to design and develop these chalcohalide materials. We then proceed to discuss their optoelectronic properties, band structures, stability, and structural chemistry employing theoretical and experimental underpinning toward high-performance devices. Next, we present an overview of recent advancements in the synthesis and their wide range of applications in energy conversion and storage devices. Finally, we conclude the review by outlining the impediments and important aspects in this field as well as offering perspectives on future research directions to further promote the development of chalcohalide materials in practical applications in the future.

Lead is widely used as a crucial elemental for lead acid batteries (LABs) and emerging halide perovskite solar cells (PSCs). However, the use of soluble lead will raise environmental concerns. For the purpose of Pb recycling, herein, we report a reactant-recycling strategy to extract Pb from used LABs and synthesize high-purity PbI 2 . The recycled PbI 2 shows smaller grain size, higher crystallinity, and higher thermal stability compared to the commercial sources. Perovskite films deposited with the high-quality PbI 2 show larger grain size and fewer defects than the commercial ones. Consequently, the synthesized PbI 2 enables a power conversation efficiency of 20.45% for the inverted MAPbI 3 (MA= methylammonium) PSCs with excellent air stability. This work offers a novel strategy for lead recovery from LABs and a green path for the realization of high-performance PSCs with high defect tolerance.

A cation substitution in Cu 2 ZnSn(S,Se) 4 (CZTSSe) offers a viable strategy to reduce the open-circuit voltage ( V oc )-deficit by altering the characteristics of band-tail states, antisite defects, and related defect clusters. Herein, we report a facile single process, i.e., simply introducing a thin Ag layer on a metallic precursor, to effectively improve the device characteristics and performances in kesterite (Ag x ,Cu 1- x ) 2 ZnSn(S y ,Se 1- y ) 4 (ACZTSSe) solar cells. Probing into the relationship between the external quantum efficiency derivative (dEQE/dλ) and device performances revealed the V oc -deficit characteristics in the ACZTSSe solar cells as a function of Cu and Ag contents. The fabricated champion ACZTSSe solar cell device showed an efficiency of 12.07% and a record low V oc -deficit of 561 mV. Thorough investigations into the mechanism underpinning the improved performance in the ACZTSSe device further revealed the improved band-tailing characteristic, effective minority carrier lifetime, and diode factors as well as reduced antisite defects and related defect clusters as compared to the CZTSSe device. This study demonstrates the feasibility of effectively suppressing antisite defects, related defect clusters, and band-tailing characteristics by simply introducing a thin Ag layer on a metallic precursor in the kesterite solar cells, which in turn effectively reduces the V oc -deficit.

A low-temperature solution-based process for depositing silver nanowire (AgNW) networks for use as transparent conductive top electrode is demonstrated. These AgNWs when applied to Cu 2 ZnSnS 4 solar cells outperformed indium tin oxide as the top electrode. Thinner nanowires allow the use of lower temperatures during processing, while longer wires allow lowered sheet resistance for the same surface coverage of NWs, enhancing the transmittance/conductance trade-off. Conductive atomic force microscopy and percolation theory were used to study the quality of the NW network at the microscale. Our optimized network yielded a sheet resistance of 18 Ω/□ and ∼95% transmission across the entire wavelength range of interest for a deposition temperature as low as of 60 °C. Our results show that AgNWs can be used for low-temperature cell fabrication using cheap solution-based processes that could also be promising for other solar cells constrained to low processing temperatures such as organic and perovskite solar cells.

Metal halide perovskite solar cells (PSCs) have undergone rapid progress. However, unstable performance caused by sensitivity to environmental moisture and high temperature is a major impediment to commercialization of PSCs. In the present work, a low-temperature, glass-glass encapsulation technique using high performance polyisobutylene (PIB) as the moisture barrier is investigated on planar glass/FTO/TiO 2 /FAPbI 3 /PTAA/gold perovskite solar cells. PIB was applied as either an edge seal or blanket layer. Electrical connections to the encapsulated PSCs were provided by either the FTO or Au layers. Results of a "calcium test" demonstrated that a PIB edge-seal effectively prevents moisture ingress. A shelf life test was performed and the PIB-sealed PSC was stable for at least 200 days. Damp heat and thermal cycling tests, in compliance with IEC61215:2016, were used to evaluate different encapsulation methods. Current-voltage measurements were performed regularly under simulated AM1.5G sunlight to monitor changes in PCE. The best results we have achieved to date maintained the initial efficiency after 540 h of damp heat testing and 200 thermal cycles. To the best of the authors' knowledge, these are among the best damp heat and thermal cycle test results for perovskite solar cells published to date. Given the modest performance of the cells (8% averaged from forward and reverse scans) especially with the more challenging FAPbI 3 perovskite material tested in this work, it is envisaged that better stability results can be further achieved when higher performance perovskite solar cells are encapsulated using the PIB packaging techniques developed in this work. We propose that heat rather than moisture was the main cause of our PSC degradation. Furthermore, we propose that preventing the escape of volatile decomposition products from the perovskite solar cell materials is the key for stability. PIB encapsulation is a very promising packaging solution for perovskite solar cells, given its demonstrated effectiveness, ease of application, low application temperature, and low cost.

An electron transport layer is essential for effective operation of planar perovskite solar cells. In this Article, PW12-TiO2 composite was used as the electron transport layer for the planar perovskite solar cell in the device structure of fluorine-doped tin oxide (FTO)-glass/PW12-TiO2/perovskite/spiro-OMeTAD/Au. A proper downward shift of the conduction band minimum (CBM) enhanced electron extraction from the perovskite layer to the PW12-TiO2 composite layer. Consequently, the common hysteresis effect in TiO2-based planar perovskite solar cells was significantly reduced and the open circuit voltage was greatly increased to about 1.1 V. Perovskite solar cells using the PW12-TiO2 compact layer showed an efficiency of 15.45%. This work can contribute to the studies on the electron transport layer and interface engineering for the further development of perovskite solar cells.

Back contact modification plays an important role in improving energy conversion efficiency of Cu2ZnSnS4 (CZTS) thin film solar cells. In this paper, an ultrathin carbon layer is introduced on molybdenum (Mo)-coated soda lime glass (SLG) prior to the deposition of CZTS precursor to improve the back contact and therefore enhance CZTS solar cell efficiency. By introducing this layer, the short circuit current (Jsc) and device conversion efficiency increase for both nonvacuum (sol-gel) and vacuum (sputtering) methods. Specifically, for the sol-gel based process, Jsc increases from 13.60 to 16.96 mA/cm(2) and efficiency from 4.47% to 5.52%, while for the sputtering based process, Jsc increases from 17.50 to 20.50 mA/cm(2) and efficiency from 4.10% to 5.20%. Furthermore, introduction of this layer does not lead to any deterioration of either open circuit voltage (Voc) or fill factor (FF).

In this work, the use of a high bandgap perovskite solar cell in a spectrum splitting system is demonstrated. A remarkable energy conversion efficiency of 23.4% is achieved when a CH3NH3PbBr3 solar cell is coupled with a 22.7% efficient silicon passivated emitter rear locally diffused solar cell. Relative enhancements of >10% are demonstrated by CH3NH3PbBr3/CH3NH3PbI3 and CH3NH3PbBr3/multicrystalline-screen-printed-Si spectral splitting systems with tandem efficiencies of 13.4% and 18.8%, respectively. The former is the first demonstration of an all perovskite split spectrum system. The CH3NH3PbBr3 cell on a mesoporous structure was fabricated by the vapor-assisted method while the planar CH3NH3PbI3 cell was fabricated by the gas-assisted method. This work demonstrates the advantage of the higher voltage output from the high bandgap CH3NH3PbBr3 cell and its suitability in a tandem system.

A facile sol-gel and selenization process has been demonstrated to fabricate high-quality single-phase earth abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic absorbers. The structure and band gap of the fabricated CZTSSe can be readily tuned by varying the [S]/([S] + [Se]) ratios via selenization condition control. The effects of [S]/([S] + [Se]) ratio on device performance have been presented. The best device shows 8.25% total area efficiency without antireflection coating. Low fill factor is the main limitation for the current device efficiency compared to record efficiency device due to high series resistance and interface recombination. By improving film uniformity, eliminating voids, and reducing the Mo(S,Se)2 interfacial layer, a further boost of the device efficiency is expected, enabling the proposed process for fabricating one of the most promising candidates for kesterite solar cells.