Periodic Reporting for period 1 - PERCISTAND (Development of all thin-film PERovskite on CIS TANDem photovoltaics)
Periodo di rendicontazione: 2020-01-01 al 2021-06-30
Estimations suggest that increased efficiency of photovoltaic (PV) appliances above the Shockley-Queisser single-junction limit is related to the creation 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.
- Opaque perovskite solar cells with efficiencies above 22% were fabricated. The stability of these cells is evaluated, and measures are taken to make them more stable. Furthermore, scalable processes were developed with efficiencies > 18% and Pb-free solar cells were investigated leading to > 6% efficiency.
- Development of highly efficient semi-transparent perovskite solar cells with stabilized power conversion efficiency of 18.5% (10.5 mm2) and 17.2% (50 mm2). Low absorbing front and rear transparent conductive electrodes and anti-reflection coatings have been implemented to enhance transmissions >90%. A database with the optical properties was created, resulting in design rules to achieve >30% in perovskite/CI(G)S tandem solar cells.
- Combining silver alloying and rubidium doping of the narrow bandgap CISe absorber led to 18.2% efficiency, thanks to a significant increase in output voltage and improved micro-structure. The uniformity of the selenium distribution in the CISe layer over an areas of 325 mm x 325 mm was much improved. An improved chemical etching protocol for smoothing CIS absorber surfaces down to a root-mean-square surface roughness of 21 nm.
- Development of common device geometries for the solar cells and modules, for demonstrating fully functional tandem devices which performance can be externally certified. Demonstration of improved semi-transparent perovskite top cells, resulting in 27.3% 4-terminal tandem cell efficiency.
- Employing optimized anti-reflective coatings at the top contact, we achieved monolithic 2-terminal tandem devices with power conversion of 20.7% on a cell area of 0.5 cm². Screening of viable hole transport materials show that a combination of low-temperature ALD processes and organic interface modifications leads to the most promising device architectures.
- Development of an energy yield model and a LCA and TEA study on perovskite solar cells. The study presents a cradle to grave environmental techno-economic assessment (ETEA) of the perovskite solar cells. The energy yield model is being used to provide energy yield values for perovskite solar cells and various 2- and 4-terminal architectures.
- Development of highly efficient semi-transparent perovskite solar cells with stabilized power conversion efficiency of 18.5% (10.5 mm2) and 17.2% (50 mm2). Low absorbing front and rear transparent conductive electrodes and anti-reflection coatings have been implemented to enhance transmissions >90%. A database with the optical properties was created, resulting in design rules to achieve >30% in perovskite/CI(G)S tandem solar cells.
- Combining silver alloying and rubidium doping of the narrow bandgap CISe absorber led to 18.2% efficiency, thanks to a significant increase in output voltage and improved micro-structure. The uniformity of the selenium distribution in the CISe layer over an areas of 325 mm x 325 mm was much improved. An improved chemical etching protocol for smoothing CIS absorber surfaces down to a root-mean-square surface roughness of 21 nm.
- Development of common device geometries for the solar cells and modules, for demonstrating fully functional tandem devices which performance can be externally certified. Demonstration of improved semi-transparent perovskite top cells, resulting in 27.3% 4-terminal tandem cell efficiency.
- Employing optimized anti-reflective coatings at the top contact, we achieved monolithic 2-terminal tandem devices with power conversion of 20.7% on a cell area of 0.5 cm². Screening of viable hole transport materials show that a combination of low-temperature ALD processes and organic interface modifications leads to the most promising device architectures.
- Development of an energy yield model and a LCA and TEA study on perovskite solar cells. The study presents a cradle to grave environmental techno-economic assessment (ETEA) of the perovskite solar cells. The energy yield model is being used to provide energy yield values for perovskite solar cells and various 2- and 4-terminal architectures.
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.