Organic light-emitting diodes (OLEDs) suffer from strong electrothermal feedback when operated with high currents. The interaction between conductivity, heat and power dissipation results in a positive feedback loop. When running an IV scan, former modeling revealed a so-called “switched-back” region where the local current density and brightness decreases although the total device current still increases.
Here, we prove the existence of a switched-back region. We demonstrate that its appearance agrees with the simulation that solely uses electrothermal modeling. Our study aims to improve the long-term stability of high brightness OLED lighting tiles e.g. as applied in the automotive sector.
Proc. SPIE. 9923, Physical Chemistry of Interfaces and Nanomaterials XV
KEYWORDS: Semiconductors, Atomic, molecular, and optical physics, Solar concentrators, External quantum efficiency, Solar cells, Clouds, Silicon solar cells, Electronic circuits, Organic semiconductors, Tandem solar cells
Current matching limits the commercialization of tandem solar cells due to their instability over spectral changes, leading to the need of using solar concentrators and trackers to keep the spectrum stable. We demonstrate that voltage-matched systems show far higher performance over spectral changes; caused by clouds, dust and other variations in atmospheric conditions.
Singlet fission is a process in organic semiconductors which has shown very efficient, 200%, down-conversion yield and the generated excitations are long-lived, ideal for solar cells. As a result, the number of publications has grown exponentially in the past 5 years. Yet, so far no one has achieved to combine singlet fission with most low bandgap semiconductors, including crystalline silicon, the dominating solar cell material with a 90% share of the PV Market.
Here we show that singlet fission can facilitate the fabrication of voltage-matched systems, opening a simple design route for the effective implementation of down-conversion in commercially available photovoltaic technologies, with no modification of the electronic circuitry of such.
The implemention of singlet fission is achieved simply by decoupling the fabrication of the individual subcells. For this demonstration we used an ITO/PEDOT/P3HT/Pentacene/C60/Ag wide-bandgap subcell, and a commercial silicon solar cell as the low-bandgap component. We show that the combination of the two leads to the first tandem silicon solar cell which exceeds 100% external quantum efficiency.