SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3577-4
Broad-absorbing materials, characterized by tunable absorption across ultraviolet to mid-infrared spectral regions, have emerged as a crucial class of optoelectronic materials. Significant advances have been achieved in organic and inorganic materials; however, current enhancement strategies remain largely platform-specific and are not guided by a unified physical framework. To address this gap, this review introduces a three-factor physical model grounded in the theory of transition probability, thereby providing a consistent theoretical basis for understanding how electronic transitions are modulated across orbital, vibrational, and spin dimensions. Structure-mechanism-performance relationships are systematically examined in classic material platforms. In addition, the contributions of external-field enhancement mechanisms, such as plasmonic resonance, to spectral broadening and local-field enhancement are discussed. Based on clear mechanistic insight and targeted materials design, recent advances in integrating broad-absorbing materials into broadband photodetectors are highlighted, emphasizing their practical relevance. The review examines the three core challenges and mechanism-driven design strategies for high-performance broadband optoelectronic systems, providing an instructive outlook for future advancements.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3593-5
Organic ultrathin crystals, comprising monolayers or a few molecular layers, exhibit outstanding optoelectronic properties and have shown great promise for constructing advanced functional neuromorphic devices. However, scalable growth of high-quality organic ultrathin crystals and their seamless concurrent integration with charge trapping layers for multi-mode neuromorphic devices, that required in future high-density neuromorphic integration, remain challenging. Here, we present a scalable one-step fabrication strategy based on solution shearing, where spontaneous vertical phase separation of a small-molecule/polymer (Ph-BTBT-10/PS) blend enables the simultaneous formation of high-quality ultrathin Ph-BTBT-10 crystals and an electret PS charge-trapping layer. The PS electret layer serves a dual function: it facilitates the formation of ultrathin, highly ordered Ph-BTBT-10 crystals; meanwhile, its gate-tunable electron-trapping capability enables dynamic switching between photo-switching and photo-synaptic modes within a single device. As a photodetector, the device exhibits exceptional performance, including a responsivity of 4.7 × 10^4 A/W, specific detectivity of 2.2 × 10^17 Jones, and photosensitivity of 1.5 × 10^8. Under negative gate bias, light-triggered switching behavior enables logic gate demonstration, while under positive gate modulation, photonic synaptic behavior successfully emulates key biological functions, including excitatory post-synaptic current (EPSC), paired-pulse facilitation (PPF), short-term plasticity (STP) to long-term plasticity (LTP) transition, dynamic learning-forgetting processes, and image processing. Moreover, the system exhibits excellent compatibility with low-voltage flexible substrates and further demonstrates its application in low-consumption flexible neuromorphic devices. This work provides a scalable route toward high-performance, multifunctional neuromorphic optoelectronics based on organic ultrathin crystals, and advances the integration of flexible electronics and brain-inspired computing.