Synergic use of two-dimensional materials to tailor interfaces in large area perovskite modules

In the field of halide perovskite solar cells (PSCs), interface engineering has been conceptualized and exploited as a powerful mean to improve solar cell performance, stability, and scalability. In this regard, here we propose the use of a multi two-dimensional (2D) materials as intra and inter layers in a mesoscopic PSCs. By combining graphene into both compact and mesoporous TiO2, Ti3C2Tx MXenes into the perovskite absorbing layer and functionalized-MoS2 at the interface between perovskite and the hole transporting layer, we boost the efficiency of PSCs (i.e., +10%) compared to the 2D materials-free PSCs. The optimized 2D materials-based structure has been successfully extended from lab-scale cell dimensions to large area module on 121 cm2 substrates (11 x11 cm2) till to 210 cm2 substrates (14.5 x14.5 cm2) with active area efficiency of 17.2% and 14.7%, respectively. The remarkable results are supported by a systematic statistical analysis, testifying the effectiveness of 2D materials interface engineering also on large area devices, extending the 2D materials-perovskite photovoltaic technology to the industrial exploitation

Graphene-Based Interconnects for Stable Dye-Sensitized Solar Modules

We present Z-Type Dye Sensitized Solar Modules (DSSMs) with screen printed graphene-based vertical interconnects. This prevents corrosion of interconnects in contact with electrolytic species, unlike conventional Ag interconnects. By enlarging the width of single cells, or by increasing the number of cells, we get an enhancement of the aperture power conversion efficiency similar to+12% with respect to Ag-based modules, with 1000 h stability under 85 degrees C stress test. This paves the way to original design layouts with decreased dead area and increased generated power per aperture area

Highly efficient 2D materials engineered perovskite/Si tandem bifacial cells beyond 29%

Perovskite/Silicon tandem technology represents a promising route to achieve 30% power conversion efficiency (PCE), by ensuring low levelized costs energy. In this article, we develop a mechanically stacked 2T perovskite/silicon tandem solar cell, with subcells independently fabricated, optimized, and subsequently coupled by contacting the back electrode of the mesoscopic perovskite top cell with the texturized and metalized front contact of the silicon bottom cell. The possibility to separately optimize the two sub-cells allows to carefully choose the most promising device structure for both top and bottom cells. Indeed, semitransparent perovskite top cell performance is boosted through the use of selected two-dimensional materials to tune the device interfaces. In addition, a protective buffer layer is used to prevent damages induced by the transparent electrode sputtering deposition over the hole transporting layer. A textured amorphous/crystalline silicon heterojunction cell fabricated with a fully industrial in-line production process is here used as state of art bottom cell. The perovskite/c-Si tandem device demonstrates remarkable PCE of 28.7%. Moreover, we demonstrate the use of a bifacial silicon bottom cell, as a viable way for overcoming the current matching constrain imposed by the 2T configuration. Here, the current generation difference between perovskite and c-Si cells is compensated by exploiting the albedo radiation thanks to the bifaciality of the commercial c-Si cell used in this article. Considering standard rear irradiation, final power generation density above 32 mW/cm(2) can be achieved, paving the way for a tandem technology customable according to the final installation site

Effects of crystal morphology on the hot-carrier dynamics in mixed-cation hybrid lead halide perovskites

Ultrafast pump-probe spectroscopies have proved to be an important tool for the investigation of charge carriers dynamics in perovskite materials providing crucial information on the dynamics of the excited carriers, and fundamental in the development of new devices with tailored photovoltaic properties. Fast transient absorbance spectroscopy on mixed-cation hybrid lead halide perovskite samples was used to investigate how the dimensions and the morphology of the perovskite crystals embedded in the capping (large crystals) and mesoporous (small crystals) layers affect the hot-carrier dynamics in the first hundreds of femtoseconds as a function of the excitation energy. The comparative study between samples with perovskite deposited on substrates with and without the mesoporous layer has shown how the small crystals preserve the temperature of the carriers for a longer period after the excitation than the large crystals. This study showed how the high sensitivity of the time-resolved spectroscopies in discriminating the transient response due to the different morphology of the crystals embedded in the layers of the same sample can be applied in the general characterization of materials to be used in solar cell devices and large area modules, providing further and valuable information for the optimization and enhancement of stability and efficiency in the power conversion of new perovskite-based devices

Low-Temperature Graphene-Based Paste for Large-Area Carbon Perovskite Solar Cells

Carbon perovskite solar cells (C-PSCs), using carbon-based counter electrodes (C-CEs), promise to mitigate instability issues while providing solution-processed and low-cost device configurations. In this work, we report the fabrication and characterization of efficient paintable C-PSCs obtained by depositing a low-temperature-processed graphene-based carbon paste atop prototypical mesoscopic and planar n-i-p structures. Small-area (0.09 cm(2)) mesoscopic C-PSCs reach a power conversion efficiency (PCE) of 15.81% while showing an improved thermal stability under the ISOS-D-2 protocol compared to the reference devices based on Au CEs. The proposed graphene-based C-CEs are applied to large-area (1 cm(2)) mesoscopic devices and low-temperature-processed planar n-i-p devices, reaching PCEs of 13.85 and 14.06%, respectively. To the best of our knowledge, these PCE values are among the highest reported for large-area C-PSCs in the absence of back-contact metallization or additional stacked conductive components or a thermally evaporated barrier layer between the charge-transporting layer and the C-CE (strategies commonly used for the record-high efficiency C-PSCs). In addition, we report a proof-of-concept of metallized miniwafer-like area C-PSCs (substrate area = 6.76 cm(2), aperture area = 4.00 cm(2)), reaching a PCE on active area of 13.86% and a record-high PCE on aperture area of 12.10%, proving the metallization compatibility with our C-PSCs. Monolithic wafer-like area C-PSCs can be feasible all-solution-processed configurations, more reliable than prototypical perovskite solar (mini)modules based on the serial connection of subcells, since they mitigate hysteresis-induced performance losses and hot-spot-induced irreversible material damage caused by reverse biases

Reevaluation of Photoluminescence Intensity as an Indicator of Efficiency in Perovskite Solar Cells

The photoluminescence (PL) intensity is often used as an indicator of the performance of perovskite solar cells and indeed the PL technique is often used for the characterization of these devices and their constituent materials. Herein, a systematic approach is presented to the comparison of the conversion efficiency and the PL intensity of a cell in both open-circuit (OC) and short-circuit (SC) conditions and its application to multiple heterogeneous devices. It is shown that the quenching of the PL observed in SC conditions is a good parameter to assess the device efficiency. The authors explain the dependence of the PL quenching ratio between OC and SC on the cell efficiency with a simple model that is also able to estimate the carrier extraction time of a device

Effect of calcination time on the physicochemical properties and photocatalytic performance of carbon and nitrogen co-doped TiO2 nanoparticles

The application of highly active nano catalysts in advanced oxidation processes (AOPs) improves the production of non-selective hydroxyl radicals and co-oxidants for complete remediation of polluted water. This study focused on the synthesis and characterisation of a highly active visible light C–N-co-doped TiO2 nano catalyst that we prepared via the sol-gel method and pyrolysed at 350 ◦C for 105 min in an inert atmosphere to prevent combustion of carbon moietie

Harnessing collective intelligence for the future of learning – a co-constructed research and development agenda

Learning, defined as the process of constructing meaning and developing competencies to act on it, is instrumental in helping individuals, communities, and organizations tackle challenges. When these challenges increase in complexity and require domain knowledge from diverse areas of expertise, it becomes difficult for single individuals to address them. In this context, collective intelligence, a capacity of groups of people to act together and solve problems using their collective knowledge, becomes of great importance. Technologies are instrumental both to support and understand learning and collective intelligence, hence the need for innovations in the area of technologies that can support user needs to learn and tackle collective challenges. Use-inspired research is a fitting paradigm that spans applied solutions and scientific explanations of the processes of learning and collective intelligence, and that can improve the technologies that may support them. Although some conceptual and theoretical work explaining and linking learning with collective intelligence is emerging, technological infrastructures as well as methodologies that employ and evidence that support them are nascent. We convened a group of experts to create a middleground and engage with the priorities for use-inspired research. Here we detail directions and methods they put forward as most promising for advancing a scientific agenda around learning and collective intelligence