Gate-tunable bipolar transport in PbSe/GeSe/MoS 2 heterojunction photodetector array for medication optical rotation detection

Low-dimensional materials with in-plane anisotropy are ideal candidates for polarization-sensitive photodetection. Based on the gate-tunable bipolar transport mechanism of field-effect transistors (FETs), by integrating anisotropic GeSe and MoS 2 with high-NIR-absorptive PbSe, we fabricated a PbSe/GeSe/MoS 2 dual-heterojunction photodetector featuring gate-tunable charge distribution. The device utilizes two distinct built-in electric fields; application of gate voltages enables precise control over interfacial charge accumulation, thereby modulating photocurrent polarity and polarization sensitivity. At zero bias, the device exhibits superior broadband photovoltaic performance, achieving a responsivity of 993 mA/W and an EQE of 131%. Furthermore, we developed a 4 × 4 photodetector array integrated with compressive sensing to facilitate rapid multi-dimensional photocurrent acquisition. Coupled with frequency modulation spectroscopy (FMS), this system enables the precise, non-destructive prediction of multi-wavelength optical rotation in liquid pharmaceuticals, demonstrating significant potential for advanced medical diagnostics.