Enhanced Fibrillar Network and Molecular Crystallization via Volatile Solid Additives Enable Efficient Near-Infrared Organic Photodetectors

Controlling the phase separation and domain purity of organic semiconductors to form well-developed nanoscale morphology optimization in the bulk-heterojunction active layer is critical yet challenging for building high-performance organic photodetectors. Herein, an effective morphology controlling method by applying a small molecule IC-Br as the solid additive is demonstrated, which can effectively restrict the overmix of the PTzBI-Si:IEICO-4F in the process of film formation. The film processed with IC-Br formed well-developed nanoscale phase separation with bi-continuous interpenetrating networks, which exhibited enhanced pi-pi stacking and the improved domain purity of the IEICO-4F phase, resulting in a significant decrease in the density of the trap state compared to the pristine film. Consequently, the device processed with IC-Br additive enabled a high specific detectivity of 3.8 x 1013 Jones at 860 nm under -0.1 V associated with the improved linear dynamic range and response speed, indicating the strong visible-to-near infrared detecting capability and potential for practical applications. The morphology optimization strategy established in this work may offer unprecedented opportunities to build state-of-the-art OPDs. An effective morphology controlling method for fabricating bulk-heterojunction film of organic photodetector is developed through incorporating a small molecule IC-Br as a solid additive into the PTzBI-Si:IEICO-4F film, which results in a significant decrease in the density of the trap state and obviously enhanced specific detectivity of 3.8 x 1013 Jones at 860 nm under -0.1 V.image