High-Polarization-Sensitivity Polarimetric Organic Phototransistors Based on Highly Stretchable Semicrystalline Polymer Semiconductors

Polarimetric phototransistors have attracted increasing interest due to their ability to recognize the polarization state of incident linearly polarized light. However, advances in their development have been hindered by the low polarization sensitivity that results from the modest polarization dichroic ratios (PDRs) of the photoactive materials. In this study, we present polarimetric organic phototransistors (P-OPTs) with a remarkably high polarization sensitivity exceeding 8.0. These P-OPTs are fabricated by transferring highly stretched (∼200%) thin films of a polymer semiconductor, poly(4-(5-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)thiophen-2-yl)-5,6-difluoro-2-octyl-7-(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole) (PCDTFBTA), which exhibits a high PDR of approximately 4.0. This improved polarization sensitivity ranks among the highest sensitivities reported for polarimetric phototransistors, demonstrating high photoresponsivity (R ≈ 500 A W–1), high external quantum efficiency (EQE ≈ 1000%), high photosensitivity (P ≈ 1.8 × 104), high specific detectivity (D* ≈ 5.9 × 1012 Jones), and short rise (τr ≈ 3.3 ms) and decay (τd ≈ 3.4 ms) times.