Printable UV detector arrays based on light-induced conductance switching in mesoporous titanium dioxide

Inkjet printed hybrid light sensors based on titanium dioxide and PEDOT:PSS

“…All optoelectronic characterization were performed in a nitrogen filled glovebox with oxygen concentration below 0.5 ppm. In fact we have verified that light response is suppressed if devices are operated under ambient air, as already assessed for titaniabased vertical devices [8]. Measurements have been performed by means of a Agilent B1500 Semiconductor Parameter Analyzer, biasing devices at 1 V. With respect to vertical devices reported in [8], this implies that the average electric field is 300 times smaller in this case.…”

“…To prepare the TiO 2 ink, a commercial titania nanoparticle paste (Dyesol DSL 18NR-T) is dissolved with a concentration of -30 mg ml 1 in a mixture of ethanol/ethylene glycole/terpineol with 0.8:0.1:0.04 relative proportions in volume. The ink, to be compatible with ink-jet printing technique and to avoid nozzle clogging, was re-engineered with a far lower concentration than the one used to spin-coat or screen-print vertical devices ( -30 mg ml 1 versus -1 g l 1 ) [8]. As a consequence, a very large (in excess of 100) number of layers proved to be necessary to deposit a film as thick as those obtained by spin-coating (in the mm range).…”

“…In this contribution, we demonstrate completely ink-jet printed UV detectors based on TiO 2 nanoparticles deposited on flexible substrates. Recently, we have demonstrated that titanium dioxide nanoparticles are amenable to the detection of UV light [8]. In contrast to the mechanism of electron/hole pairs photogeneration usually exploited in photodetectors, TiO 2 was shown to undergo a n-type photodoping upon UV exposure that results in conductance switching in excess of six orders of magnitude after few seconds of exposure to radiation of few mW cm −2 .…”

Investigation of the transient photo-response and switching window of an Al/indigo/Al device: unveiling negative photoconductivity and the photo-enhanced memory window

“…42 Among the photodetectors, UV detectors have been widely used in many fields, such as fire detection, chemical sensing, monitoring of skin exposure, combustion monitoring, forensic application, and security scanning systems, and in radiation dose control in biomedical applications. [43][44][45] Reducing the operational voltage of UV detectors is a challenge. In 2017, a UV detector array with an operational voltage of 1 V was demonstrated using titanium dioxide (TiO 2 ).…”

“…In 2017, a UV detector array with an operational voltage of 1 V was demonstrated using titanium dioxide (TiO 2 ). 45 Reduced operational voltage and improved retention of photo-enhanced memristors are highly desired. The photo-enhanced resistive switching technique has the potential to provide substantial advantages in situations calling for long-term endurance and retention, suggesting reliable non-volatile information storage efficiency.…”