High-performance polymer tandem devices combining solar cell and light-emitting diode

We demonstrate high-performance polymer tandem devices (PTDs) combining solar cell (SC) and light-emitting diode (LED), which are fabricated using solution-based techniques for each layer with the use of semiconducting and metallic polymers. The PTD has three terminals—two outer electrodes and an internal common electrode—and functions as a SC and a LED. In the SC mode, the PTD exhibits a reasonable power conversion efficiency of 3.1% under AM 1.5 irradiation conditions, whereas the device functions as a LED with a luminance of 8000 cd/m2 when applying external bias voltages. A sol–gel processed titanium sub-oxide (TiOx) is efficiently used in the PTDs for carrier transport toward the target electrode.