Scalable-Production, Self-Powered TiO2 Nanowell-Organic Hybrid UV Photodetectors with Tunable Performances.

Hybrid inorganic-organic photoelectric devices draw considerable attention because of their unique features by combining the tunable functionality of organic molecules and the superior intrinsic carrier mobilities of inorganic semiconductors. An ordered thin layer of TiO2 nanowells is formed in situ with shallow nanoconcave patterns without cracking with scalable production by a facile and economic strategy, and these layers are used as building blocks to construct hybrid UV photodetectors (PDs). Organic conducting polymers (polyaniline (PANI) with various morphologies) have been exploited as p-type materials, enabling tunable photodetection performances at zero bias. The thin layer of n-type TiO2 nanowells is favorable for electron transport and light absorption with respect to their conventional nanotubular counterparts, while PANI acts as a hopping state or bridge to largely enhance the transition probability of the valence electrons in TiO2 to its conduction band, resulting in an increase in photocurrent in a self-powered mode. In particular, the lowest polyaniline loading sample (TP1) exhibits the highest responsivity (3.6 mA·W-1), largest on-off switching ratio (∼103), excellent wavelength selectivity, fast response speed (3.8/30.7 ms), and good stability under 320 nm light illumination (0.56 mW·cm-2) without an external energy supply. This work might be of great value in developing tunable UV photoresponse materials with respect to low cost and a large area for future energy-efficient optoelectronic devices.