Robust and Recyclable Substrate Template with an Ultrathin Nanoporous Counter Electrode for Organic-Hole-Conductor-Free Monolithic Perovskite Solar Cells

Achievements, challenges, and future prospects for industrialization of perovskite solar cells

In just over a decade, certified single-junction perovskite solar cells (PSCs) boast an impressive power conversion efficiency (PCE) of 26.1%. Such outstanding performance makes it highly viable for further development. Here, we have meticulously outlined challenges that arose during the industrialization of PSCs and proposed their corresponding solutions based on extensive research. We discussed the main challenges in this field including technological limitations, multi-scenario applications, sustainable development, etc. Mature photovoltaic solutions provide the perovskite community with invaluable insights for overcoming the challenges of industrialization. In the upcoming stages of PSCs advancement, it has become evident that addressing the challenges concerning long-term stability and sustainability is paramount. In this manner, we can facilitate a more effective integration of PSCs into our daily lives.

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.

Eco-design for perovskite solar cells to address future waste challenges and recover valuable materials

Photovoltaic development should be steered by the circular economy. However, it is not. In case of perovskite photovoltaics even current environmental directives divert from profitably recycling. Here, we study the profitability of noble metals recovery from wasted perovskite solar cells depending on recycling routes. Our results show that substrates play a major role in the recovery of precious metals and in contrast to previous research even recycling carbon-based devices could reach profitability. Going beyond the recovery of valuable elements, our findings show that revival of the perovskite solar cells is strongly dependent on the device architecture, so far viable for mesoscopic structures with carbon back contacts. Perovskite solar cells are still at the development stage, but the window of opportunity to ensure eco-design will close with market entry, and device complexity might compromise profitability recycling and even result in failure of recovery critical materials. Therefore, its eco-design should be prioritized by materials researchers to develop devices, where valuable components can be separated and liberated with safe and low energy processes.

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.

Green energy by recoverable triple-oxide mesostructured perovskite photovoltaics

Perovskite solar cells have developed into a promising branch of renewable energy. A combination of feasible manufacturing and renewable modules can offer an attractive advancement to this field. Herein, a screen-printed three-layered all-nanoparticle network was developed as a rigid framework for a perovskite active layer. This matrix enables perovskite to percolate and form a complementary photoactive network. Two porous conductive oxide layers, separated by a porous insulator, serve as a chemically stable substrate for the cells. Cells prepared using this scaffold structure demonstrated a power conversion efficiency of 11.08% with a high open-circuit voltage of 0.988 V. Being fully oxidized, the scaffold demonstrated a striking thermal and chemical stability, allowing for the removal of the perovskite while keeping the substrate intact. The application of a new perovskite in lieu of a degraded one exhibited a full regeneration of all photovoltaic performances. Exclusive recycling of the photoactive materials from solar cells paves a path for more sustainable green energy production in the future.

Recycled Utilization of a Nanoporous Au Electrode for Reduced Fabrication Cost of Perovskite Solar Cells

Perovskite solar cells (PSCs) using metal electrodes have been regarded as promising candidates for next-generation photovoltaic devices because of their high efficiency, low fabrication temperature, and low cost potential. However, the complicated and rigorous thermal deposition process of metal contact electrodes remains a challenging issue for reducing the energy pay-back period in commercial PSCs, as the ubiquitous one-time use of a contact electrode wastes limited resources and pollutes the environment. Here, a nanoporous Au film electrode fabricated by a simple dry transfer process is introduced to replace the thermally evaporated Au electrode in PSCs. A high power conversion efficiency (PCE) of 19.0% is demonstrated in PSCs with the nanoporous Au film electrode. Moreover, the electrode is recycled more than 12 times to realize a further reduced fabrication cost of PSCs and noble metal materials consumption and to prevent environmental pollution. When the nanoporous Au electrode is applied to flexible PSCs, a PCE of 17.3% and superior bending durability of ≈98.5% after 1000 cycles of harsh bending tests are achieved. The nanoscale pores and the capability of the porous structure to impede crack generation and propagation enable the nanoporous Au electrode to be recycled and result in excellent bending durability.

Recycling of FTO/TiO2 Substrates: Route toward Simultaneously High-Performance and Cost-Efficient Carbon-Based, All-Inorganic CsPbIBr2 Solar Cells

Carbon-based, all-inorganic perovskite solar cells (PSCs) have drawn enormous attention recently on account of their ungraded stability and reduced costs. However, their power conversion efficiencies (PCEs) still lag behind the ones with conventional architecture. Moreover, the high cost of FTO substrates and energy-consuming sintering process of TiO₂ electron-transporting layers should be further addressed. Herein, it is demonstrated that the FTO/TiO₂ substrates could be separated simply from degraded CsPbIBr₂ PSCs for fabricating the new ones again, which thus reduces the production costs of resulting PSCs and makes them renewable and sustainable. Meanwhile, the characterization results reveal that there are some residual CsPbIBr₂-derived species on recycled FTO/TiO₂ substrates, which enable the upper CsPbIBr₂ films with suppressed halide phase separation and reduced defects, the diminished work function of TiO₂ layers from 4.13 to 3.89 eV, along with decreased conduction band minimum (CBM) difference of CsPbIBr₂/TiO₂ interface from 0.51 to 0.36 eV. Consequently, the average PCE of CsPbIBr₂ PSCs is improved by 20%, from 6.51 ± 0.62% to 8.14 ± 0.63%, wherein the champion one yields the exceptional value of 9.12%. These findings provide an avenue for simultaneous performance enhancement and cost-saving of carbon-based, all-inorganic PSCs to promote their commercialization.

Enhanced Efficiency of Carbon-Based Mesoscopic Perovskite Solar Cells through a Tungsten Oxide Nanoparticle Additive in the Carbon Electrode

This paper presents perovskite solar cells employed with WO₃ nanoparticles embedded carbon top electrode. WO₃ nanoparticles works as an inorganic hole-transport material (HTM) to promote the hole-extraction in the perovskite/carbon interface as revealed by efficiency, electrochemical impedance and external quantum efficiency measurements. As a result, a 40% enhancement of energy conversion efficiency has been achieved compared to the reference devices with the energy conversion efficiency of 10.77% under standard conditions. In addition, the Li-TFSI can modify the interface between electron-transport material (ETM) and perovskite, which may inhibit the recombination at the ETM/perovskite interface. The V_OC of devices upon the modification of Li-TFSI is increased from 887.9 to 934.2 mV. This work highlights about the enlightenment of the effective performance of carbon-based mesoscopic PSCs by the introduction of HTM and the modification of interfaces.