Galindo , S.; Ahmadpour, M.; Guerling, L.; Marsal, A.; Voz, C.; Alcubilla, R.; Puigdollers, J. Organic electronics Vol. 15, num. 10, p. 2553-2560 DOI: 10.1016/j.orgel.2014.07.011 Data de publicació: 2014-10-01 Article en revista
Open-circuit voltages are strongly dependent on the density-of-states in solar cells based on disordered semiconductors. In this work, organic solar cells based on tetraphenyldibenzoperiflanthene and fullerene C-70 with a bilayer structure were fabricated to investigate the variation in the density-of-states with the substrate temperature during deposition of the donor. The maximum open circuit voltage was reached at a substrate temperature of 60 degrees C. Organic thin-film transistors were also fabricated to study their electrical properties, such as the mobility and the density-of-states. Finally, an organic solar cell with p-i-n structure was fabricated at the optimized substrate temperature, and a power conversion efficiency of almost 4% was obtained. (C) 2014 Elsevier B.V. All rights reserved.
Marsal, A.; Carreras, P.; Puigdollers, J.; Voz, C.; Galindo , S.; Alcubilla, R.; Bertomeu, J.; Antony, A. Thin solid films Vol. 555, p. 107-111 DOI: 10.1016/j.tsf.2013.08.010 Data de publicació: 2014-03-31 Article en revista
In this work, zinc indium tin oxide layers with different compositions are used as the active layer of thin film transistors. This multicomponent transparent conductive oxide is gaining great interest due to its reduced content of the scarce indium element. Experimental data indicate that the incorporation of zinc promotes the creation of oxygen vacancies, which results in a higher free carrier density. In thin-film transistors this effect leads to a higher off current and threshold voltage values. The field-effect mobility is also strongly degraded, probably due to coulomb scattering by ionized defects. A post deposition annealing in air reduces the density of oxygen vacancies and improves the field-effect mobility by orders of magnitude. Finally, the electrical characteristics of the fabricated thin-film transistors have been analyzed to estimate the density of states in the gap of the active layers. These measurements reveal a clear peak located at 0.3 eV from the conduction band edge that could be attributed to oxygen vacancies. (C) 2013 Elsevier B.V. All rights reserved.
Pentacene and N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13H27) have been used as organic semiconductors for the fabrication of p-type and n-type organic thin-film transistors (OTFTs). Both types of semiconductors are well-established and demonstrate good performance in single devices, but few competitive results have been reported in complementary circuits. In this manuscript, we show the fabrication, electrical characterization and simulation of an organic complementary inverter using pentacene and PTCDI-C13 as active semiconductors. Simulation was done using a model with physical aspects. We report good fitting of p-type and n-type parameters for the OTFT model and good results for DC transfer characteristics of the organic complementary inverter. The fitting of the parameters of the OTFT model is performed using an optimized parameter extraction technique which is using fuzzy logic to adjust the parameters to its optimal value.
Picene has recently attracted much attention as the active layer in organic thin-film transistors because of its good performance in air. In this work, we have fabricated picene thin-film transistors that exhibit field-effect mobilities up to 1.3 cm2 V−1 s−1 and on/off ratios above 105 in ambient conditions. These devices have been electrically characterized over the temperature range 300–360 K in air and also under vacuum conditions. In particular, the thermal activation energy of the channel conductance as a function of the gate bias has been measured. The dependence of the activation energy on the gate bias corresponds to a gradual shift of the Fermi level towards the HOMO level as more gap states are filled by trapped holes. The density-of-states can be estimated from the derivative of the activation energy with respect to gate bias. The calculated density-of-states is compared for devices measured in air and under vacuum conditions. These results can help to understand the gas sensing capability of picene, together with its enhanced electrical performance after air exposure.
Puigdollers, J.; Marsal, A.; Voz, C.; Della Pirriera, M.; Cheylan, S.; Alcubilla, R. International Conference on Synthetic Materials p. 252 Data de presentació: 2010-07-06 Presentació treball a congrés
Puigdollers, J.; Pirriera, D.; Marsal, A.; Orpella, A.; Cheylan, S.; Voz, C.; Alcubilla, R. Thin solid films Vol. 517, num. 23, p. 6271-6274 DOI: 10.1016/j.tsf.2009.02.113 Data de publicació: 2009-10 Article en revista