Recycling of Perovskite Films: Route toward Cost-Efficient and Environment-Friendly Perovskite Technology

Uniform, Fully Connected, High-Quality Monocrystalline Freestanding Perovskite Oxide Films Fabricated from Recyclable Substrates

Releasing epitaxial perovskite oxide films from their native oxide substrates produces high quality, 2D-material-like monocrystalline freestanding oxide membranes, as potential key components for the next-generation electronic devices. Two major obstacles still limit their practical applications: macroscopic material defects (mainly cracks) that lowers uniformity and yield, and the high cost of the consumed oxide substrates. Here, a two-step film transfer method and a substrate recycling method enable repetitive fabrication of millimeter-scale, fully-connected freestanding oxide films of various chemical compositions from the same substrates; arrays of capacitor and resistor devices based on these oxides transferred on silicon indicate high uniformity, low sample-to-sample variation, and satisfactory electrical connectivity. The two-step transfer suppresses crack formation by avoiding buckling-delamination-type relaxation of epitaxial strain, and the key point to achieve substrate reuse is to remove the residual Al species bonded to the substrate surfaces. The mitigation of such long-lasting issues in freestanding oxide fabrication techniques may eventually pave roads toward future industrial-grade devices, as well as enabling many research opportunities in fundamental physics.

Highly effective biosorption capacity of Cladosporium sp. strain F1 to lead phosphate mineral and perovskite solar cell PbI2

Fungus Cladosporium sp. strain F1 showed highly effective biosorption capacity to lead phosphate mineral and perovskite solar cells lead iodide compared to other fungi Aspergillus niger VKMF-1119 and Mucor ramannianus R-56. Scanning electron microscopy and transmission electron microscopy analyses shows that Cladosporium sp. strain F1, which previously showed high biosorption capacity to uranium phosphate nanorods and nanoplates, can accumulate lead phosphate mineral and lead iodide on the fungal hyphae surface in large amounts under a wide range of pH conditions, while A. niger VKMF-1119 and M. ramannianus R-56 adsorbed small amounts of minerals. After biosorption of lead iodide minerals on Cladosporium sp. strain F1, aqueous dimethyl sulfoxide (50%) at pH 2 (70 °C) released the mineral more than 99%. Based on the fungal surface analyses, hydrophobic properties on the surfaces of Cladosporium sp. strain F1 could affect the higher biosorption capacity of strain F1 to lead phosphate mineral and lead iodide as compared to other tested fungi. Cladosporium sp. strain F1 may be the novel biosorbents to remediate the phosphate rich environment and to recover lead from perovskite solar cells lead iodide.

Full Life-Cycle Lead Management and Recycling Transparent Conductors for Low-Cost Perovskite Solar Cell

Realizing a full life-cycle management for toxic lead (Pb) and reducing material/manufacture cost are the key steps in determining the commercialization process of perovskite photovoltaics. In this work, we develop full lifecycle material management for a carbon-based perovskite solar cell (C-PSC) to immobilize and recover Pb against environmental pollution, followed by refabrication of C-PSC based on recovered materials and recycled transparent conductors from obsolete devices. Pb immobilization is first achieved by a strong coordination interaction between undercoordinated Pb ions from perovskite and a C═O bond from green pseudohalide ions (pseudo-X), and the resulting C-PSC with the structure of ITO/SnO₂/pseudo-X-perovskite/carbon yields an efficiency of 16.63%. Pb from an end-of-life C-PSC is then recovered by dissolving the obsolete perovskite layer into DMF/DMSO precursor solvent, followed by replenishing a certain amount of MAI to guarantee new perovskite layer formation. The refabricated C-PSC based on recovered perovskite and a recycled transparent conductor displays comparable efficiency (15.30%) to that of C-PSC with commercial raw materials, also exceeding the previous efficiency record for C-PSCs based on recycled materials. Such refabricated C-PSC is relatively low-cost.

Progress in Perovskite Solar Cells towards Commercialization-A Review

In recent years, perovskite solar cells (PSCs) have experienced rapid development and have presented an excellent commercial prospect as the PSCs are made from raw materials that are readily and cheaply available depending on simple manufacturing techniques. However, the commercial production and utilization of PSCs remain immature, leading to substantial efforts needed to boost the development of scalable fabrication of PSCs, pilot scale tests, and the establishment of industrial production lines. In this way, the PSCs are expected to be successfully popularized from the laboratory to the photovoltaic market. In this review, the history of power conversion efficiency (PCE) for laboratory-scale PSCs is firstly introduced, and then some methods for maintaining high PCE in the upscaling process is displayed. The achievements in the stability and environmental friendliness of PSCs are also summarized because they are also of significance for commercialization. Finally, this review evaluates the commercialization prospects of PSCs from the economic view and provides a short outlook.

The critical issue of using lead for sustainable massive production of perovskite solar cells: a review of relevant literature

This work aims to review the most significant studies dealing with the environmental issues of the use of lead in perovskite solar cells (PSCs). A careful discussion and rationalization of the environmental and human health toxicity impacts, evaluated by life cycle assessment and risk assessment studies, is presented. The results of this analysis are prospectively related to the possible future massive production of PSC technology.

Dialkylamines Driven Two-Step Recovery of NiOx/ITO Substrates for High-Reproducibility Recycling of Perovskite Solar Cells

Because of the toxicity of water-soluble lead, the recycling of organic-inorganic lead-halides perovskite solar cells (PSCs) has attracted increasing attention. Here, we report a highly reliable two-step process to recycle cost-dominated indium-tin-oxide (ITO) substrates coated with NiO_x and regenerate their based PSCs by function of dialkylamines. The champion recycled PSC can achieve 20% in conversion-efficiency, higher than 17.92% of the fresh one. Strikingly, the regenerated devices can remain superior to the fresh ones in the first 7 of 10 recycles. The comprehensive X-ray photoelectronic spectroscopy analysis reveals that dipropylamine has a suitable interaction with NiO_x surfaces by Ni-N coordination, enabling its effective interfacial passivation and template effect of high-quality growth of perovskites. That leads to the suppressed nonradiative recombination of both interfacial and bulk, and finally improves the device performances. The dialkylamines driven two-step recycling process offers a promising and highly reproducible strategy to recycle PSCs, especially the cost-dominated NiO_x/ITO substrates.

Recovery of FTO coated glass substrate via environment-friendly facile recycling perovskite solar cells

Organic-inorganic perovskite solar cells (PSCs) have recently emerged as a potential candidate for large-scale and low-cost photovoltaic devices. However, the technology is still susceptible to degradation issues and toxicity concerns due to the presence of lead (Pb). Therefore, investigation on ideal methods to deal with PSC wastes once the device attains its end-of-life is crucial and to recycle the components within the cell is the most cost effective and energy effective method by far. This paper reported on a layer-by-layer extraction approach to recycle the fluorine-doped tin oxide (FTO) coated glass substrate which is the most expensive component in the device architecture of mesoporous planar PSC. By adapting the sequential removal of each layer, chemical properties of individual components, including spiro-OMeTAD and gold can be preserved, enabling the material to be easily reused. It also ensured that the toxic Pb component could be isolated without contaminating other materials. The removal of all individual layers allows the retrieval of FTO conductive glass which can be used in various applications that are not only restricted to photovoltaics. Comparison of electrical, morphological and physical properties of recycled FTO glasses to commercial ones revealed minimal variations. This confirmed that the recycling approach was useful in retrieving the substrate without affecting its physicochemical properties.

Orientation-Controlled (h0l) PbI2 Crystallites Using a Novel Pb-Precursor for Facile and Quick Sequential MAPbI3 Perovskite Deposition

Organic-inorganic hybrid lead halide perovskites have shown significant progress in the last few years having achieved efficiencies over 25% at the lab scale. The sequential deposition technique has provided a robust approach in the perovskite film fabrication. However, obtaining a reproducible and quality perovskite film has always been challenging because of the highly crystalline and ordered (001) oriented underlying PbI₂ film. Here, we report a simple solution approach to fabricate a PbI₂ residue-free, superior grade perovskite film by using a compositional engineered PbI₂-precursor solution. We demonstrate that the Pb-precursor film crystallized into a R-centered Hexagonal metric lattice with (h0l), (hk0), and (00l) orientations provides a more efficient and quicker conversion into perovskites compared to conventional (001) oriented 2H-PbI₂. A porous and multi-oriented PbI₂ film is prepared by rationally incorporating a volumetric fraction of Pb(Ac)₂·3H₂O in the typical PbI₂/dimethylformamide precursor solution, which significantly improves the surface features of PbI₂ as well as the structural properties. As a result, a compact, smooth, and large grain perovskite can be obtained by accomplishing a full conversion with comparatively much less reaction time. Furthermore, a comprehensive mechanism of structural modification of PbI₂ and the role of its orientation in ameliorating the reaction kinetics has been demonstrated.

Historical Analysis of High-Efficiency, Large-Area Solar Cells: Toward Upscaling of Perovskite Solar Cells

The status and problems of upscaling research on perovskite solar cells, which must be addressed for commercialization efforts to be successful, are investigated. An 804 cm² perovskite solar module has been reported with 17.9% efficiency, which is significantly lower than the champion perovskite solar cell efficiency of 25.2% reported for a 0.09 cm² aperture area. For the realization of upscaling high-quality perovskite solar cells, the upscaling and development history of conventional silicon, copper indium gallium sulfur/selenide and CdTe solar cells, which are already commercialized with modules of sizes up to ≈25 000 cm² , are reviewed. GaAs, organic, dye-sensitized solar cells and perovskite/silicon tandem solar cells are also reviewed. The similarities of the operating mechanisms between the various solar cells and the origin of different development pathway are investigated, and the ideal upscaling direction of perovskite solar cells is subsequently proposed. It is believed that lessons learned from the historical analysis of various solar cells provide a fundamental diagnosis of relative and absolute development status of perovskite solar cells. The unique perspective proposed here can pave the way toward the upscaling of perovskite solar cells.

Don't Let the Lead Out: New Material Chemistry Approaches for Sustainable Lead Halide Perovskite Solar Cells

Lead halide perovskites are seriously considered for next generation photovoltaic technology. They have a unique combination of easy synthesis, high efficiency, and cost-effective techniques. Still, the major concern is the toxicity of lead used in perovskite devices. The research community is still debating whether the amount of lead used in a solar cell really poses a danger or not. However, it is pretty clear that mitigating the lead leakage from the lead halide perovskite device is of utmost importance. In this review, we discuss new material chemistry approaches that can be applied to reduce the lead leakage/wastage from damaged lead halide perovskite solar cells. ECR (encapsulate, capture, and recycle) approaches have the potential to significantly reduce the environmental and health hazard risks of lead halide perovskite devices. Encapsulation by a self-healing material and rigid glass can help the perovskite survive the extreme conditions and avoid exposure of the perovskite layer to the external environment. Capturing of lead can also be done by an encapsulant layer that can very quickly and efficiently bind to lead, in the case that it leaks from the damaged perovskite device. Moreover, the recycling of damaged or decommissioned devices helps to avoid the lead wastage and contamination in the environment. Finally, we also discuss the potential of lead-free perovskite for optoelectronic applications.

Unravelling the Photocatalytic Behavior of All-Inorganic Mixed Halide Perovskites: The Role of Surface Chemical States

Within the most mesmerizing materials in the world of optoelectronics, mixed halide perovskites (MHPs) have been distinguished because of the tunability of their optoelectronic properties, balancing both the light-harvesting efficiency and the charge extraction into highly efficient solar devices. This feature has drawn the attention of analogous hot topics as photocatalysis for carrying out more efficiently the degradation of organic compounds. However, the photo-oxidation ability of perovskite depends not only on its excellent light-harvesting properties but also on the surface chemical environment provided during its synthesis. Accordingly, we studied the role of surface chemical states of MHP-based nanocrystals (NCs) synthesized by hot-injection (H-I) and anion-exchange (A-E) approaches on their photocatalytic (PC) activity for the oxidation of β-naphthol as a model system. We concluded that iodide vacancies are the main surface chemical states that facilitate the formation of superoxide ions, O₂^●-, which are responsible for the PC activity in A-E-MHP. Conversely, the PC performance of H-I-MHP is related to the appropriate balance between band gap and a highly oxidizing valence band. This work offers new insights on the surface properties of MHP related to their catalytic activity in photochemical applications.