High-reproducibility production of solution processable near-infrared organic photodiode materials and inks for the image sensor industry

In this study, we focus on the precise control of electronic and ink properties for hole transport materials (HTM) and photoactive materials, consisting of p-type polymers (donors) and non-fullerene acceptors (NFA), to develop solution processable near-infrared (NIR) and short-wave infrared (SWIR) organic photodiodes(OPDs) with consistent performance over different batches. We observed fluctuations in the turn-on voltage of NIR-OPD devices when using different batches of our HTM. Regression analysis revealed a strong correlation between the turn-on voltage and specific factors in the polymer. By implementing an improved purification scheme, we successfully suppressed these fluctuations. Moreover, we investigated the impact of p-type polymer structure and properties on device performance and solubility in non-halogenated solvents. A trade-off between molecular weight and EQE of NIR-OPDs was identified in a commercially purchased polymer. However, by optimizing the synthesis pathway, we achieved compatibility between these parameters in our polymer and extended the ink storage period to over three months without compromising EQE and dark current. Additionally, we introduce a novel NFA, IR6, which exhibits an impressive EQE of 45% at 1100 nm with a dark current of 4 × 10 ⁻⁵ mA/cm⁻² . These advancements in precise material control and novel NFA offer promising prospects for the commercialization of solution-processable NIR-OPDs, making them viable candidates for high-performance near-infrared sensing applications.