Despite the impressive photovoltaic performances with power conversion efficiency beyond 22%, perovskite solar cells are poorly stable under operation, failing by far the market requirements. Various technological approaches have been proposed to overcome the instability problem, which, while delivering appreciable incremental improvements, are still far from a market-proof solution. Here we show one-year stable perovskite devices by engineering an ultra-stable 2D/3D (HOOC(CH2)4NH3)2PbI4/CH3NH3PbI3 perovskite junction. The 2D/3D forms an exceptional gradually-organized multi-dimensional interface that yields up to 12.9% efficiency in a carbon-based architecture, and 14.6% in standard mesoporous solar cells. To demonstrate the up-scale potential of our technology, we fabricate 10 × 10 cm2 solar modules by a fully printable industrial-scale process, delivering 11.2% efficiency stable for >10,000 h with zero loss in performances measured under controlled standard conditions. This innovative stable and low-cost architecture will enable the timely commercialization of perovskite solar cells.

We investigated a range of different mesoporous NiO electrodes prepared by different research groups and private firms in Europe to determine the parameters which influence good quality photoelectrochemical devices. This benchmarking study aims to solve some of the discrepancies in the literature regarding the performance of p-DSCs due to differences in the quality of the device fabrication. The information obtained will lay the foundation for future photocatalytic systems based on sensitized NiO so that new dyes and catalysts can be tested with a standardized material. The textural and electrochemical properties of the semiconducting material are key to the performance of photocathodes. We found that both commercial and non-commercial NiO gave promising solar cell and water-splitting devices. The NiO samples which had the two highest solar cell efficiency (0.145% and 0.089%) also gave the best overall theoretical H2 conversion.

Among the new photovoltaic technologies, the Dye-Sensitized Solar Cell (DSC) is becoming a realistic approach towards energy markets such as BIPV (Building Integrated PhotoVoltaics). In order to improve the performances of DSCs and to increase their commercial attractiveness, cheap, colourful, stable and highly efficient ruthenium-free dyes must be developed. Here we report the synthesis and complete characterization of a new purely organic sensitizer (RK1) that can be prepared and synthetically upscaled rapidly. Solar cells containing this orange dye show a power conversion efficiency of 10.2% under standard conditions (AM 1.5G, 1000 Wm−2) using iodine/iodide as the electrolyte redox shuttle in the electrolyte, which is among the few examples of DSC using an organic dyes and iodine/iodide red/ox pair to overcome the 10% efficiency barrier. We demonstrate that the combination of this dye with an ionic liquid electrolyte allows the fabrication of solar cells that show power conversion efficiencies of up to 7.36% that are highly stable with no measurable degradation of initial performances after 2200 h of light soaking at 65°C under standard irradiation conditions. RK1 achieves one of the best output power conversion efficiencies for a solar cell based on the iodine/iodide electrolyte, combining high efficiency and outstanding stability.

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A novel family of six donor-acceptor type organic sensitizers for dye-sensitized solar cells (DSSCs) is reported. The dyes have been designed to have outstanding light absorption properties in the visible range and being able to achieve high photon-to-electrical current conversion for BIPV (building-integrated photovoltaic). Moreover, stability tests under illumination at 1 Sun and 65 1C showed a great stability for some of the devices, with less than 6% decrease of power conversion efficiency after 3000 hours. The differences in the performance of the six sensitizers under standard illumination conditions can be correlated with the observed differences in the photo-induced transient photovoltage and in charge extraction measurements. We report the use of one of the dyes for the fabrication of semi-transparent solar modules showing an active area of 1400 cm 2 and a power output of 10.5 W m -2 . Broader contextTremendous progress has been achieved in the past decade in the effciency of dye-sensitized mesoscopic solar cells (DSSC), owing to the development of new metal-free organic sensitizers. To increase their commercial attractiveness and to make them a realistic approach towards energy markets such as BIPV (building integrated photovoltaics), the new dyes must be cheap, colorful, and effcient, and moreover they must show a high stability. In this paper, we report a family of donor-acceptor type metal-free photosensitizers with simple structures for DSSCs. The precise molecular design of the dyes leads to a quite narrow light absorption in the visible range and a high photon-to-electrical current conversion in solar cells. These organic sensitizers that can be prepared in few steps show power efficiencies over 10% when they are used with iodine-based liquid electrolytes. Stability tests and fabrication of semitransparent solar modules with an active area of 1400 cm 2 demonstrate the potential of these organic dyes for large scale applications and mass production for BIPV.

One of the key challenges of perovskite photovoltaics (PV) is the long‐term stability. Although efforts are made to improve the lifetime of perovskite PV devices, their degradation under reverse‐bias conditions is barely addressed. Herein, perovskite solar cells with carbon‐based electrodes are presented which demonstrate superior resilience against reverse‐bias‐induced degradation. Although their breakdown voltage is identified to be at approximately −3.6 V, cells do not degrade until the applied reverse‐bias exceeds −9 V. Two main degradation mechanisms are identified: 1) iodine loss due to hole tunneling into perovskite, which takes place even at low reverse‐bias but decomposes the perovskite only after long time durations; and 2) rapid heating at large reverse‐bias leading to formation of PbI2, which starts at shunts and then follows the path of the least resistance for the cell current, which is primarily influenced by the electrode sheet resistances. Finally, perovskite solar modules with carbon‐based electrodes are demonstrated, which are subjected to a “hotspot” test described in the IEC 61215:2016 international standard at an accredited module testing laboratory. Passing this accelerated test for the first time confirms the superior stability of perovskite PV devices with carbon‐based electrodes and highlights their large industrialization potential.

New benzothiadiazole-based dyes are synthesized, characterized and used for the fabrication of robust and efficient solar cells and mini-modules.

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