• Energy Research

The optical and photovoltaic properties of Si NCs / SiC multilayers (MLs) are investigated using a membrane-based solar cell structure. By removing the Si substrate in the active cell area, the MLs are studied without any bulk Si substrate contribution. The occurrence is confirmed by scanning electron microscopy and light-beam induced current mapping . Optical characterization combined with simulations allows us to determine the absorption within the ML absorber layer, isolated from the other cell stack layers. The results indicate that the absorption at wavelengths longer than 800 nm is only due to the SiC matrix. The measured short-circuit current is significantly lower than that theoretically obtained from absorption within the ML absorber, which is ascribed to losses that limit carrier extraction. The origin of these losses is discussed in terms of the material regions where recombination takes place. Our results indicate that carrier extraction is most efficient from the Si NCs themselves, whereas recombination is strongest in SiC and residual a-Si domains . Together with the observed onset of the external quantum efficiency (EQE) at 700-800 nm, this fact is an evidence of quantum confinement in Si NCs embedded in SiC on device level.

The optical and photovoltaic properties of Si NCs / SiC multilayers (MLs) are investigated using a membrane-based solar cell structure. By removing the Si substrate in the active cell area, the MLs are studied without any bulk Si substrate contribution. The occurrence is confirmed by scanning electron microscopy and light-beam induced current mapping . Optical characterization combined with simulations allows us to determine the absorption within the ML absorber layer, isolated from the other cell stack layers. The results indicate that the absorption at wavelengths longer than 800 nm is only due to the SiC matrix. The measured short-circuit current is significantly lower than that theoretically obtained from absorption within the ML absorber, which is ascribed to losses that limit carrier extraction. The origin of these losses is discussed in terms of the material regions where recombination takes place. Our results indicate that carrier extraction is most efficient from the Si NCs themselves, whereas recombination is strongest in SiC and residual a-Si domains . Together with the observed onset of the external quantum efficiency (EQE) at 700-800 nm, this fact is an evidence of quantum confinement in Si NCs embedded in SiC on device level.

Lead-free PEA2SnI4-based perovskite LEDs are successfully inkjet-printed on rigid and flexible substrates. Red-emitting devices (λmax = 633 nm) exhibit, under ambient conditions, a maximum external quantum efficiency (EQEmax) of 1% with a related brightness of 30 cd/m2 at 10 mA/cm2.

Lead-free PEA2SnI4-based perovskite LEDs are successfully inkjet-printed on rigid and flexible substrates. Red-emitting devices (λmax = 633 nm) exhibit, under ambient conditions, a maximum external quantum efficiency (EQEmax) of 1% with a related brightness of 30 cd/m2 at 10 mA/cm2.

AbstractWe offer a complete structural and optical study of samples containing silicon nanocrystals (Si-NCs) embedded in SiO2/SiON multilayers, varying the oxynitride layer thickness from 2.5 to 7nm. Using energy-filtered transmission electron microscopy we have determined the size distribution of the precipitated Si-nanoaggregates. Raman scattering measurements were used to investigate the Si-NC size and crystalline quality. By combining both techniques, the nanoaggregate crystalline degree has been evaluated, with values around 50% for all the samples. Photoluminescence spectroscopy has shown a blueshift of the emission at smaller NC sizes, presenting the sample with Si-NCs of 3.9nm the best emission properties.

AbstractWe offer a complete structural and optical study of samples containing silicon nanocrystals (Si-NCs) embedded in SiO2/SiON multilayers, varying the oxynitride layer thickness from 2.5 to 7nm. Using energy-filtered transmission electron microscopy we have determined the size distribution of the precipitated Si-nanoaggregates. Raman scattering measurements were used to investigate the Si-NC size and crystalline quality. By combining both techniques, the nanoaggregate crystalline degree has been evaluated, with values around 50% for all the samples. Photoluminescence spectroscopy has shown a blueshift of the emission at smaller NC sizes, presenting the sample with Si-NCs of 3.9nm the best emission properties.

AbstractInkjet printing has emerged as a promising technique for the fabrication of halide perovskite (HP) thin films, as it enables precise and controlled deposition of the perovskite ink on a variety of substrates. One main advantage of inkjet printing for the fabrication of HP thin films is its ability to produce uniform films with controlled thickness and high coverage, which is critical for achieving high‐performance devices. Additionally, inkjet printing allows for the deposition of patterned thin films, enabling the fabrication of complex device architectures such as light‐emitting diodes (LEDs). In this work, flexible LEDs based on inkjet printed Pb‐free HP thiophene‐ethylammonium tin iodide (TEA2SnI4) are produced that has gained attention as a potential alternative to Pb‐based HPs in optoelectronic devices due to its lower toxicity, environmental impact, and high performance. The role of ink solutions is compared using pure solvents: toxic dimethyl formamide (DMF) and more eco‐friendly dimethyl sulfoxide (DMSO). Red‐emitting devices (λmax = 633 nm) exhibit, in ambient conditions, a maximum external quantum efficiency (EQEmax) of 0.5% with a related brightness of 21 cd m−2 at 54 mA cm−2 for DMSO‐based LEDs. The environmental impacts of films prepared with DMSO‐based solvents ensure only 40% of the impact caused by DMF.