In this work, the fabrication of MoOx-free semitransparent perovskite solar cells (PSC) with Power Conversion Efficiencies (PCE) up to 15.7% is reported. Firstly, opaque PSCs up to 19.7% were fabricated. Then, the rear metal contact was replaced by a highly transparent and conductive indium tin oxide (ITO) film, directly sputtered onto the hole selective layer, without any protective layer between Spiro-OMeTAD and rear ITO. To the best of our knowledge, this corresponds to the most efficient buffer layer-free semitransparent PSC ever reported. Using time-resolved photoluminescence (TRPL) technique on both sides of the semitransparent PSC, Spiro-OMeTAD/perovskite and perovskite/TiO2 interfaces were compared, confirming the great quality of Spiro-OMeTAD/perovskite interface, even after damage-less ITO sputtering, where degradation phenomena result less important than for perovskite/TiO2 one. Finally, a 4-terminal tandem was built combining semitransparent PSC with a commercially-available Aluminium Back Surface Field (Al-BSF) silicon wafer. That silicon wafer presents PCE = 19.52% (18.53% after being reduced to cell size), and 5.75% once filtered, to generate an overall 4 T tandem efficiency of 21.18% in combination with our champion large semitransparent PSC of 15.43%. It means an absolute increase of 1.66% over the original silicon wafer efficiency and a 2.65% over the cut Si cell.

Development of industrially relevant thin‐film deposition processes is a necessity for upscaling the perovskite solar cell technology to commercial product‐level. This work reports on a sequential deposition method for state‐of‐the art triple cation perovskite by slot‐die coating. During this two‐step process, first, a layer of lead iodide mixed with cesium iodide is deposited, followed by applying the organic cations on top, inducing conversion to perovskite during a second slot‐die coating step. By carefully tuning the ink composition and the deposition parameters, uniform perovskite layers of 5 × 10 cm2 are obtained. Power conversion efficiencies up to 19% for small laboratory solar cells adopting a planar device configuration and up to 15.2% for mini‐modules with an aperture area of 12 cm2 are presented. These values are among the highest efficiencies achieved in the literature for slot‐die‐coated perovskite.

We study a micro-concentrated photovoltaic (CPV) system based on micro solar cells made from a thin film technology, Cu(In,Ga)Se₂. We designed, using the ray-tracing software Zemax OpticStudio 14, an optical system adapted and integrated to the microcells, with only spherical lenses. The designed architecture has a magnification factor of 100× for an optical efficiency of 85% and an acceptance angle of ±3.5°, without anti-reflective coating. An experimental study is realized to fabricate the first generation prototype on a 5  cm×5  cm substrate. A mini-module achieved a concentration ratio of 72× under AM1.5G, and an absolute efficiency gain of 1.8% for a final aperture area efficiency of 12.6%.

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