Simultaneous enhancement of photocurrent and open circuit voltage in ternary organic solar cells by red fluorescent material as third component materials

Ternary organic solar cells (OSCs) were constructed using D18-Cl:Y6 as the host photoactive layer and the red fluorescent material [4-(dicyano-methylene)-2-methyl-6-(p-dimethyl aminostyryl)-4H-pyran] (DCM) as the third component material. The optimized ternary OSCs (optimized weight ratio of D18-Cl:Y6:DCM is 1:1.4:0.1) showed a power conversion efficiency (PCE) of 17.36 %, a short-circuit current density (JSC) of 26.79 mA cm-2, an open-circuit voltage (VOC) of 0.89 V, and a fill factor (FF) of 72.8 %. Since the absorption peak of DCM is located in the red light region and the photoluminescence peak of DCM is covered by the absorption peak of D18Cl, DCM significantly improves the short-wavelength light absorption of the optimized ternary photoactive layer and facilitates the energy transfer from DCM to D18-Cl. While increasing the DCM content, the LUMO level of the blend acceptor is shifted upwards, which favors the VOC value. However, excessive amount of DCM would damage the phase separation, bulk and surface morphology of the ternary film. The results showed that the red fluorescent material DCM has great potential as a third component material for realizing highly efficient ternary OSCs.