Wang Xin, Gao Shijia, Han Jinfeng, Liu Zhipeng, Qiao Wenqiang, Wang Zhi Yuan
State Key Laboratory of Fine Chemicals, Department of Polymer Science & Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China.
Department of Materials Science and Engineering and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States.
ACS Appl Mater Interfaces. 2022 Jun 3. doi: 10.1021/acsami.2c04775.
Reducing the dark current density and enhancing the overall performance of the device is the focal point in research for organic photodetectors. Two novel random terpolymers (P3 and P4) with different molecular weights are synthesized and evaluated as acceptors in bulk heterojunction (BHJ) polymer photodetectors. Compared with known acceptor materials, such as N2200 (P1) and F-N2200 (P2), polymer P4 has a lower lowest unoccupied molecular orbital (LUMO) energy level, favorable morphology, and good miscibility with a donor material J71, which leads to proper phase separation of the blend film and better dissociation of excitons and transport of carriers. Therefore, a considerably low dark current density () of 1.9 × 10 A/cm and a high specific detectivity (*) of 1.8 × 10 cm Hz/W (also "Jones") at 580 nm under a -0.1 V bias are realized for the P4-based photodetector. More importantly, the device also exhibits a fast response speed (τ/τ = 1.24/1.87 μs) and a wide linear dynamic range (LDR) of 109.2 dB. This work demonstrates that high-performance all-polymer photodetectors with ideal morphology can be realized by random polymer acceptors with a fine-tuned molecular weight.
降低暗电流密度并提高器件的整体性能是有机光电探测器研究的重点。合成了两种具有不同分子量的新型无规三元共聚物（P3和P4），并将其作为本体异质结（BHJ）聚合物光电探测器中的受体进行评估。与已知的受体材料，如N2200（P1）和F-N2200（P2）相比，聚合物P4具有更低的最低未占据分子轨道（LUMO）能级、良好的形态以及与供体材料J71的良好混溶性，这导致共混膜有适当的相分离以及更好的激子解离和载流子传输。因此，基于P4的光电探测器在-0.1 V偏压下于580 nm处实现了相当低的暗电流密度（），为1.9×10 A/cm，以及高比探测率（*），为1.8×10 cm Hz/W（也称为“琼斯”）。更重要的是，该器件还表现出快速的响应速度（τ/τ = 1.24/1.87 μs）和109.2 dB的宽线性动态范围（LDR）。这项工作表明，通过具有微调分子量的无规聚合物受体可以实现具有理想形态的高性能全聚合物光电探测器。
