Fig. 1. OPD device structure^[4]. (a) Organic photoconduction; (b) OPT; (c) organic photodiode

Fig. 2. Schematic diagrams of heterojunction classification in organic photodiode. (a) Schematic diagram of PHJ structure; (b) schematic diagram of BHJ structure

Fig. 3. Classification based on detection range. (a)(b) Full-color OPD^[31]; (c) narrowband OPD^[32]; (d) color selective OPD^[33]

Fig. 4. Schematic diagram of device structure and performance of ternary blend NIR-OPD^[41]

Fig. 5. Schematic diagram of structure and performance of IDC-based NIR eutectic OFET^[45]

Fig. 6. Bulk heterostructure, planar heterostructure, and molecular structure diagrams of PbPc and C₇₀ and absorption spectra of PbPc∶ C₇₀ and PbPc/C₇₀^［54］. (a) PbPc and C₇₀ bulk heterostructure; (b) PbPc and C₇₀ planar heterostructure; (c) PbPc and C₇₀ molecular structure; (d) absorption spectra of PbPc∶C₇₀ and PbPc/C₇₀

Fig. 7. Schematic diagrams of material absorption curves, external quantum efficiency, responsivity, specific detectability curves, and device structure. (a)(b) Absorption curves and external quantum effect curves of PC₆₁BM as receptor material^[55]; (c)(d) absorption curves, photoresponsivity and detectability spectra of conjugated dimeric porphyrin small molecules and PC₇₁BM^[56]; (e) absorption spectra of Por4IC and P3HT blend films^[57]; (f) schematic diagram of ultra-thin TFT-CN device ^[58]

Fig. 8. Schematic diagrams of spectral absorption and responsivity curves, device structure, and energy level. (a) Spectral absorption curves and responsivity of intrinsic BHJ^[60]; (b) response rate curves^[60]; (c)‒(e) schematic diagrams of NIR-OPD structure and device responsivity R and specific detection rate D^* at -0.5 V^[61]; (f) schematic diagram of BHJ device structure with inverted structure^[62]; (g) material energy level diagram^[62]; (h)‒(i) responsivity and specific detection rate D^* of the device at different bias voltages^[62]

Fig. 9. Schematic diagrams of working principle and optoelectronic characteristics^[74]. (a) Schematic diagram of the working principle of organic semiconductor charge collection narrowing; (b) device spectral absorption and EQE

Fig. 10. Schematic diagrams of resonator structure and absorption spectra^[75]. (a) Schematic diagram of the structure of a tunable oscillator OPD; (b) normalized absorption spectra

Fig. 11. Schematic diagrams of device structure and energy level distribution^[76]. (a) Schematic diagram of device structure; (b) schematic diagram of photoactive layer of PM6∶Y6 OPD device; (c) absorption photon distribution of NIR wavelength in thick and thin photodiode structure; (d) energy level distribution of OPD

Fig. 12. Schematic diagrams of device structure and I-V characteristics^[89]. (a) Basic structure of the device; (b) schematic diagram of I-V characteristics

Fig. 13. Schematic diagrams of exciton and responsivity distribution^[94]. (a) Distribution of exciton generation after top and bottom light incidence in PHJ device; (b) distribution of excitons after top and bottom light incidence in BHJ device; (c) distribution of PHJ device structure and dual band device responsivity

Fig. 14. NIR-OPD applications. (a) Schematic diagram of integrated circuit response for medical health monitoring^[96]; (b) schematic diagram of basic structure of NIR-OPD^[96]; (c) test diagram of transmissive pulse signal monitoring^[97]; (d) schematic diagram of flexible integrated PPG^[98]; (e) schematic diagram of biological imaging^[97]; (f) flexible OPD prepared based on hydrogel substrate ^[98]; (g) demultiplexing process in dual channel optical communication applications^[99]; (h) schematic diagram of imaging of NIR-II OPD array based on YZ1^[100]