Examinando por Autor "Martín-Martín, Diego"

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Influence of solvent additive on the performance and aging behavior of non-fullerene organic solar cells
(Elsevier, 2022) Arredondo, Belén; Pérez-Martínez, José Carlos; Muñoz-Díaz, Laura; López-González, Maria del Carmen; Martín-Martín, Diego; Pozo, Gonzalo del; Hernández-Balaguera, Enrique; Romero, Beatriz; Lamminaho, Jani; Turkovic, Vida; Madsen, Morten
The performance of organic solar cells has improved significantly in recent years due to the use of non-fullerene acceptors (NFA). While processing additives are typically added to the active layer blends to enhance device performance in NFA organic solar cells, their impact on device degradation remains unclear. In this work we have compared the performance, in pristine and degraded state, between air-processed slot-die coated NFA ITOfree organic solar cells with and without the processing additive DIO, using a structure of PET/Ag/ZnO/PBDB-T: ITIC/FHC PEDOT:PSS. We observed an improvement in the power conversion efficiency of the devices when adding DIO, from 4.03% up to 4.97%. The evolution of the performance for both devices under ISOS-L1 life testing protocol reveals that the drop in efficiency is mainly due to a decay of JSC for both cells. In the short time scale the efficiency of non-DIO cells decays faster than the DIO cells, whereas in the long time scale the efficiency of non-DIO cells tends to stabilize sooner. Carrier mobilities estimated from impedance measurements decrease with time at similar rate for both degraded samples. Besides, DIO devices present a steep increase of the series resistance with time causing a decrease of the FF and thus of the efficiency. Moreover, in both degraded devices, the open-circuit voltage saturates with increasing illumination intensity. Numerical simulations reveal that a reduced anode work function of 5 eV is needed to fit experimental data.
Temperature behaviour of mixed-cation mixed-halide perovskite solar cells. Analysis of recombination mechanisms and ion migration
(Elsevier, 2023) López-González, Mari Carmen; Pozo, Gonzalo del; Arredondo, Belén; Delgado, Silvia; Martín-Martín, Diego; García-Pardo, Marina; Romero, Beatriz
In our study, we show that compositional engineering of the “A” site cation of ABX3 perovskite structure formed by a mix of organic and inorganic cations is an effective route to improve the thermal stability of perovskite solar cells (PSCs). In this work, mixed-cation mixed-halide PSCs have been fabricated and characterized with temperature, from 253 up to 333 K. The active layer based on CsRbFAMAPb(IBr)3 results in a more stable device compared to standard MAPbI3 devices. Electrical characterization reveals a decrease of the solar cell parameters with temperature. Using Impedance Spectroscopy (IS) characterization, we have estimated an activation energy for the halide ion migration of 0.63 ± 0.08 eV, an ion diffusion coefficient of 10− 14 cm2 s − 1 , and a defect density of 7.27⋅1015 cm− 3 . To our knowledge, this is the first time that these parameters have been calculated in CsRbFAMAPb(IBr)3 based devices, resulting in improved values compared to MAPbI3 devices. The worsening of device performance for temperatures above 300 K is attributed to a decrease of the spiro-OMeTAD conductivity and the degradation of the perovskite/spiro-OMeTAD interface. It is shown that for low temperatures (from 253 to 323 K), Shockley-Red-Hall (SRH) recombination in the bulk governs, while for temperatures above 323 K the increase in surface recombination becomes dominant due to the presence of non-selective contacts. Numerical simulations using SILVACO ATLAS corroborate the role of SRH in the perovskite active layer for low and medium temperatures, and the crucial influence of spiro-OMeTAD transport properties in the device performance parameters.
Unraveling Conductive Filament Formation in High Performance Halide Perovskite Memristor
(Wiley, 2024-07-02) Pérez-Martínez, José Carlos; Martín-Martín, Diego; Arredondo, Belèn; Romero, Beatriz
This study examined the differences between children and adolescents with autism spectrum disorder (ASD) and neurotypically developing (NTD) in terms of balance, postural control, and motor skills. It also examined which motor skills are most affected and whether scores on different assessment tests in ASD children are correlated. A cross-sectional observational study with two research groups was conducted. Timed up and go test (TUG), short form of Bruininks-Oseretsky test of Motor Proficiency version 2 (SFBOT-2), and pediatric balance scale (PBS) were used. A total of 100 participants 50 with ASD and 50 with NTD engaged in the research. Statistically significant differences were obtained between control group and ASD group in TUG test and in SFBOT-2 standard score and total score (p-value = <0.01). A statistically significant difference (p-value = <0.01) was seen between ASD group's and control group's PBS scores. Poor correlation was noted between TUG and SFBOT-2, as well as between PBS and TUG. A moderate correlation was also found between SFBOT-2 and PBS. Children with ASD present difficulties in motor skills and in static and dynamic balance compared to children with NTD. Differences were observed in the motor skills of strength followed by manual dexterity, running speed and agility, fine motor precision, fine motor integration, and balance. The PBS item that showed the greatest difference between the ASD group and control group was maintaining monopodial support with hands on hips. Finally, poor to moderate correlations were obtained between the different tests with statistically significant differences