Post-Treated Self-Assembled Monolayer-Driven Low-Noise Self-Powered Organic Photonic Conversion Devices

초록

Combining energy harvesting and photodetection within a single organic device enables self-powered sensing platforms to be built around integrated photodetector (PD) photovoltaics. The hole transport layer (HTL) of these devices governs the charge extraction dynamics that determine their performance. [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz), a widely used self-assembled monolayer HTL offering a modified work function (WF) and simple solution processing, forms surface aggregates during deposition that degrade the interfacial uniformity and raise the trap density at the hole-extracting contact. To address this limitation, a posttreatment with 2-chloronicotinic acid (INA) is applied to the 2PACz interface. INA reduces the surface aggregates and restores the interfacial uniformity while preserving the established ability of 2PACz to modify the WF. A PM6:L8-BO-based device using a treated interface delivers power conversion efficiencies of 16.7% under 1-sun (AM 1.5 G) and 29.8% under 1000 lx illumination (2700 K LED) in the PV mode. In self-powered PD mode, the treated device exhibits low noise current of 9.19 fA and a directly measured noise equivalent power of 40.4 fW (device area = 0.1 cm2, bandwidth = 1 Hz), corresponding to a specific detectivity of 7.81 & times; 1012 cm & centerdot;Hz1/2 & centerdot;W-1 and a linear dynamic range of 147.7 dB.

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