A novel type of tunable organic photovoltaic (OPV) tandem device with ionic gating by in-situ ionic liquid is presented. This device is comprised of two solution-processed polymeric OPV cells connected in parallel by a dry-laminated transparent multiwall carbon nanotube (MWCNT) interlayer. The interlayer MWCNT of this 3-terminal tandem device plays a role of a common electrode with a Fermi level that can be tuned via ionic gating to turn it into a common cathode, collecting photo-generated electrons from both sub-cells. Ionic gating employs electric double layer charging of the MWCNT in order to lower the work function of the common CNT electrode and increase its n-type conductivity. This tandem device is fabricated in ambient conditions via dry-lamination of MWCNT transparent sheets The new results demonstrating the different regimes of ionic gating at low, medium, and high gating voltages Vgate are presented, showing the optimal doping of the MWCNT, then favorable doping of acceptor PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), followed by the deterioration of performance at Vgate over the threshold voltage when doping of polymeric layers of sub-cell OPVs starts taking place. The doping of PCBM and polymers is additionally confirmed by the change in the charging and discharging current dynamics at high Vgate above the threshold.
The n-type and p-type a-GaN films were successfully grown on a r-sapphire substrate, according to X-ray diffractometer and SEM results parameters measurement. The growth rate versus the growth temperature was investigated. The holes concentration (8x1017 cm−3) was achieved by the Cp2Mg flow optimization and the parameters of thermal annealing in nitrogen. The GaN film growth rate dependence versus temperature at a constant hydrogen flow through a TEG source was investigated. The results indicate that defects density is reduced upto 104 cm−2, the surface morphology uniformity was improved. During growth the influence from V/III flows ratio was detected.
Organic photovoltaics, based on hybrid inorganic organic optoelectronic perovskites, with structure alkali-metal-halide are the newest emerging technology in the third generation development. Despite tremendous efficiency records, more than 21 %, optoelectronic perovskites' instability prevents their commercialization and mass production. Issues with degradation are caused by various types of environmental influences. The main issues with stability and power loss in devices are linked to moisture, oxygen, temperature, and light-induced structure defects. Initial measurements are taken after long term debugging with minimal aggressive exposure to environmental conditions. In this case, preliminary degradation studies begin from measurements of light-induced effects. In this work, we will present the main trends in degradation of external characteristics during common I-V measurements, in the order of parameters which were effected the least by environmental factors. This investigation was made on fixed CH3NH3PBI3 solar cells with standard 1.5 AM testing and initial efficiencies more than 8 %.
This article presents the results of research output voltage characteristics of solar cells on an organic basis with the use of P3HT: PCBM system. There were produced organic solar cells in a coating in air, current-voltage characteristics were measured. It was determined the characteristic influence of a substrate cleaning and annealing temperature of layers applied on fill factor and conversion efficiency.
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