High External Quantum Efficiency and Ultra‐Narrowband Organic Photodiodes Using Single‐Component Photoabsorber With Multiple‐Resonance Effect

Organic photodiodes (OPDs) that utilize wavelength-selective absorbing molecules offer a direct approach to capturing specific wavelengths of light in multispectral sensors/imaging systems without filters. However, they exhibit broad response bandwidths, low external quantum efficiency (EQE), and often require compromises in two-component photoactive materials. Herein, the first utility of boron-nitrogen (BN) single-component photoabsorbers, leveraging a multi-resonance effect are introduced to attain OPDs with both record-high EQE of 33.77% and ultra-small full-width half-maximum (FWHM) of 36 nm in the reported narrowband OPDs using single-component photoabsorbers. It is found that the outstanding performance of these narrowband OPDs can be attributed to the ultra-small FWHM, slow charge recombination, low activation energy, and balanced bipolar charge transport within the para-tert-butyl substituted B,N-embedded rigid polycyclic molecule (BNCz) film. Furthermore, BN derivatives such as BN(p)SCH₃, BN(p)SO₂CH₃, and pyBN-m-H have also shown high EQE, minimal FWHM, and tunable photoresponse peaks ranging from blue-violet to blue-turquoise, highlighting the potential of BN molecules and molecular engineering in the development of novel narrowband absorbers for advanced wavelength-selective OPDs. Such pioneering working can provide a class of novel narrowband absorbers to propel the advancement of high-performance wavelength-selective OPDs.