A realistic approach to increase the efficiency of photovoltaic (PV) devices above the Shockley-Queisser single-junction limit is the construction of tandem devices. PERCISTAND focuses on the development of advanced materials and processes for all thin film perovskite on chalcogenide tandem devices. This tandem configuration is at an early stage of development today. The PERCISTAND emphasis is on 4-terminal tandem solar cell and module prototype demonstration on glass substrates, but also current- and voltage-matched 2-terminal proof-of-concept device structures are envisaged. Key research activities are the development and optimization of top wide band gap perovskite and bottom low band gap CuInSe2 devices, suitable transparent conductive oxides, and integration into tandem configurations. The focus is on obtaining high efficiency, stability and large-area manufacturability, at low production cost and environmental footprint. Efficiency target is 30 % at cell level, and 25 % at module level. Reliability and stability, tested in line with International Electrotechnical Commission (IEC) standards, must be similar as commercially available PV technologies. High manufacturability means that all technologies applied are scalable to 20×20 cm2, using sustainable and low-cost materials and processes. The cost and environmental impact will be assessed in line with International Organization for Standardization (ISO), and must be competitive with existing commercial PV technologies. Such a tandem device significantly outperforms not only the stand-alone perovskite and chalcogenide devices, but also best single-junction silicon devices. The development will be primarily on glass substrates, but also applicable to flexible substrates and thus interesting for building integrated photovoltaic (BIPV) solutions, an important market for thin film PV. Hence, the outcome has high potential to strengthen and regain the EU leadership in thin film PV research and manufacturing.

Prime objective of the Sharc25 project is to develop super-high efficiency Cu(In,Ga)Se2 (CIGS) solar cells for next generation of cost-beneficial solar module technology with the world leading expertise establishing the new benchmarks of global excellence. The project partners ZSW and EMPA hold the current CIGS solar cell efficiency world records of 21.7% on glass and 20.4% on polymer film, achieved by using high (~650°C) and low (~450°C) temperature CIGS deposition, respectively. Both have developed new processing concepts which open new prospects for further breakthroughs leading to paradigm shift for increased performance of solar cells approaching to the practically achievable theoretical limits. In this way the costs for industrial solar module production 100 MW production capacity, with further scopes for cost reductions through production ramp-up. In this project the performance of single junction CIGS solar cells will be pushed from ~21% towards 25% by a consortium with multidisciplinary expertise. The key limiting factors in state-of-the-art CIGS solar cells are the non-radiative recombination and light absorption losses. Novel concepts will overcome major recombination losses: combinations of increased carrier life time in CIGS with emitter point contacts, engineered grain boundaries for active carrier collection, shift of absorber energy bandgap, and bandgap grading for increased tolerance of potential fluctuations. Innovative approaches will be applied for light management to increase the optical path length in the CIGS absorber and combine novel emitter, front contact, and anti-reflection concepts for higher photon injection into the absorber. Concepts of enhanced cell efficiency will be applied for achieving sub-module efficiencies of >20% and industrial implementation strategies will be proposed for the benefit of European industries.