Rational Molecular Design of π‐Extended Thiazolothiazole for High‐Performance UV‐OPDs Seamlessly Integrated with CMOS

Abstract

AbstractVacuum‐deposited organic photodiodes (OPDs) offer unique advantages—including narrowband selectivity and compatibility with standard fabrication processes—but achieving ultraviolet (UV) selectivity in such devices remains a key challenge. This is due to the need to reconcile two competing design requirements: 1) strong π–π stacking for efficient charge transport, and 2) limited π‐conjugation to retain a wide bandgap suitable for UV absorption and vacuum deposition. Here, we report a molecular design strategy for UV‐selective OPDs based on thiazolothiazole (Tz)‐based small molecules with tailored backbone planarity and conjugation length. The resulting vacuum‐deposited active layers simultaneously exhibit wide bandgaps and robust π–π interactions. The optimized devices achieve outstanding UV selectivity (full‐width at half‐maximum: 60 nm), high specific detectivity (1.06 × 1012 Jones), and fast dynamic response (cutoff frequency of 50,100 Hz)—representing the highest performance for vacuum‐deposited UV‐OPDs reported to date. Furthermore, it is demonstrated the seamless integration of these semi‐transparent OPDs with complementary metal‐oxide‐semiconductor (CMOS) image sensors (CIS), underscoring their potential for multifunctional imaging applications. The findings provide key molecular insights for advancing UV‐selective organic photodetectors.