The researchers engineered a special ink formulation to print wavelength-selective bulk heterojunction organic photodetectors onto flexible carriers. They incorporated nonfullerene acceptors in a transparent polymer donor matrix to narrow and tune the optical response in the visible range without optical filters or light management techniques.
In the KIT team’s approach, the optical properties of the bulk heterojunction system are decoupled from the viscoelastic ink properties. The spectral response of the device depends solely on the choice of nonfullerene acceptor, while the polymer donor dictates the properties of the ink. This removes any interdependence between processing parameters and the optical properties of the active layer. It eliminates the need for devising new ink formulations when selecting a different nonfullerene acceptor and simplifies the process of developing and printing filterless, wavelength-selective organic photodetectors.