Efficient inkjet-printed blue OLED with boosted charge transport using host doping for application in pixelated display

Inkjet-printing is a desirable technology for organic light emitting diodes (OLEDs) owing to its compatibility with large-area low-cost full-color pixelated displays. In this work, we proposed a strategy to fabricate highly efficient inkjet-printed blue OLEDs by introducing 3,5-bis(N-car-bazolyl)benzene (mCP) as the host material into organic light emitting layers. By carefully tailoring the weight ratio of mCP to poly[(9,9-dioctyl-2,7-fluorene)-co-(dibenzothiophene-S,S-dioxide)] (PFSO), the device demonstrated superior charge transport capability, leading to balanced charge transport and optimized efficiency. Furthermore, in combination with modifying the mCP: PFSO ink formulation, a low-roughness organic emissive film on Poly(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) layer was achieved. The performance of the inkjet-printed device has been significantly improved with nearly five times, which exhibits a maximum luminance and an external quantum efficiency of 3743 cd/m2 and 5.03%, respectively. The icing on the cake is that we fabricated a 3-inch blue OLED array device successfully with a brightness uniformity of 92.7%, which shows promising potential in realizing simple structure large-area and high-efficient OLEDs by inkjet printing.