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Cu(In,Ga)Se2 based ultrathin solar cells the pathway from lab rigid to large scale flexible technology
Publication . Lopes, T.S.; Teixeira, J. P.; Curado, M. A.; Ferreira, B. R.; Oliveira, A. J. N.; Cunha, J. M. V.; Monteiro, M.; Violas, A.; Barbosa, J. R. S.; Sousa, P. C.; Çaha, I.; Borme, J.; Oliveira, K.; Ring, J.; Chen, W. C.; Zhou, Y.; Takei, K.; Niemi, E.; Deepak, F. L.; Edoff, M.; Brammertz, G.; Fernandes, P. A.; Vermang, B.; Salomé, P. M. P.
The incorporation of interface passivation structures in ultrathin Cu(In,Ga)Se2 based solar cells is shown. The fabrication used an industry scalable lithography technique—nanoimprint lithography (NIL)—for a 15 × 15 cm2 dielectric layer patterning. Devices with a NIL nanopatterned dielectric layer are benchmarked against electron-beam lithography (EBL) patterning, using rigid substrates. The NIL patterned device shows similar performance to the EBL patterned device.The impact of the lithographic processes in the rigid solar cells’ performance were evaluated via X-ray Photoelectron Spectroscopy and through a Solar Cell Capacitance Simulator. The device on stainless-steel showed a slightly lower performance than the rigid approach, due to additional challenges of processing steel substrates, even though scanning transmission electron microscopy did not show clear evidence of impurity diffusion. Notwithstanding, time-resolved photoluminescence results strongly suggested elemental diffusion from the flexible substrate. Nevertheless, bending tests on the stainless-steel device demonstrated the mechanical stability of the CIGS-based device.
Over 100 mV VOC improvement for rear passivated ACIGS ultra‐thin solar cells
Publication . Oliveira, Antonio; Rocha Curado, Marco; Teixeira, J. P.; Tomé, Daniela; Çaha, Ihsan; Oliveira, Kevin; Lopes, Tomás; Monteiro, Margarida; Violas, André; Correira, Maria; Fernandes, Paulo; Deepak, Francis; Edoff, Marika; Salomé, Pedro
A decentralized energy system requires photovoltaic solutions to meet new aesthetic paradigms, such as lightness, flexibility, and new form factors. Notwithstanding, the materials shortage in the Green Transition is a concern gaining momentum due to their foreseen continuous demand. A fruitful strategy to shrink the absorber thickness, meeting aesthetic and shortage materials consumption targets, arises from interface passivation. However, a deep understanding of passivated systems is required to close the efficiency gap between ultra-thin and thin film devices, and to mono-Si. Herein, a (Ag,Cu)(In,Ga)Se2 ultra-thin solar cell, with 92% passivated rear interface area, is compared with a conventional nonpassivated counterpart. A thin MoSe2 layer, for a quasi-ohmic contact, is present in the two architectures at the contacts, despite the passivated device narrow line scheme. The devices present striking differences in charge carrier dynamics. Electrical and optoelectronic analysis combined with SCAPS modelling suggest a lower recombination rate for the passivated device, through a reduction on the rear surface recombination velocity and overall defects, comparing with the reference solar cell. The new architecture allows for a 2% efficiency improvement on a 640 nm ultra-thin device, from 11% to 13%, stemming from an open circuit voltage increase of 108 mV.
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Fundação para a Ciência e a Tecnologia
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PDQI_NORTE
Funding Award Number
2020.07073.BD