Efficient SWIR Organic Photodetectors with Spectral Detection Extending to 1.4 µm Using a Benzobisthiadiazole-Based Acceptor
Organic photodetectors (OPDs) offer significant advantages in biomedical
applications, including medical imaging, heart rate monitoring, and
tumor therapy. Despite advancements in OPD technology, the efficiency of
these devices in the short-wave infrared (SWIR) region remains
considerably lower than that of inorganic semiconductors. To tackle this
challenge, this study developed an ultra-narrow bandgap acceptor of
CS-1, featuring an A-D-A1-D-A structure where benzobisthiadiazole (BBT) serves as the electron-deficient unit A1,
which exhibits a wide absorption range from 300 to 1550 nm. This
molecular design not only enhances the absorption properties of the
material but also improves the overall performance of the OPD device. It
is worth noting that the optimal PTB7-Th:CS-1 device realizes a
specific detectivity (Dn*) of 2.96 × 1010 Jones at 1.30 µm, making it one of the most efficient devices at this
wavelength to date. Additionally, it demonstrates the high linear
dynamic range (LDR) of 91.9 dB even at 1300 nm. These results indicate
that the PTB7-Th:CS-1 device significantly enhances detection efficiency
in the SWIR region, surpassing most commercially available
silicon-based photodetectors. This highlights the significant potential
of the BBT unit for achieving high-performance SWIR OPDs.
