Ternary organic photodiodes with spectral response from 300 to 1200 nm for spectrometer application

The light spectrometer is one of the most widely used optical instruments, allowing users to measure and analyze spectral components. However, to reach a broad spectral response range, most spectrometers have to combine a silicon photodiode with an additional photodiode to account for the limited operating wavelength range of each in isolation. Here, we developed organic photodiodes (OPDs) by combining a novel narrow-bandgap non-fullerene acceptor (COTIC-4Cl) with a polymer donor (PCE10) in the presence of PC71BM as the third component. The resulting device based on the ternary blended material showed a wide spectral response from 300 to 1200 nm, beyond the response range of the traditional silicon-based photodiode. Moreover, at the wavelength of 1100 nm, the resulting OPD exhibited a specific detectivity of 5 × 1012 Jones and a responsivity of 0.3 A W−1, with a cut-off frequency of >1 MHz and a linear dynamic range of >120 dB, among the best performances of OPDs. Of particular importance is that, as a proof-of-concept, the resulting ternary OPD was successfully utilized as the key component of a spectrometer to measure the absorption across 300–1200 nm. These results indicate the potential applications of the broadband response OPDs for next-generation spectrometers.