Achieving high-performance organic photodetectors with novel interpenetrated heterojunction architectures

Heterojunctions are indispensable for fabricating high-performance organic photodetectors. However, traditional structures—such as planar heterojunctions (PHJs) and bulk heterojunctions (BHJs)—face significant challenges. PHJs often suffer from limited exciton dissociation in thick films, while BHJs experience considerable charge transport barriers. Although quasi-planar heterojunctions have been proposed to address these issues, controlling their nanoscale interface remains complex and material-dependent, limiting their applications. Herein, we introduce novel interpenetrated heterojunctions (IPHJs), formed by penetrating a secondary organic semiconductor layer into a porous bottom layer during annealing. This innovative structure is revealed to possess efficient exciton dissociation and charge transport. Remarkably, organic photodiodes (OPDs) featuring PM6:N2200 IPHJs demonstrate exceptional performance, achieving a responsivity (R) of 36.5 A/W, a specific detectivity (D*) of 8.6 × 1012 Jones, and a response time (τ) of 30 μs, representing state-of-the-art performance for OPDs. Furthermore, extending the IPHJ concept to tri-layer interpenetrated heterojunctions (T-IPHJs) shows significant promise for organic phototransistor applications. The PM6:N2200 T-IPHJ devices exhibit a responsivity exceeding 44.7 A/W, a D* value reaching 5.23 × 1014 Jones, and a τ of 70 ms. These results show the potential of IPHJs to advance the field of high-performance organic photodetectors and related devices.