Abstract
In this study, we present a highly integrated design of organic optoelectronic devices for Point-of-Need (PON) nitrite () measurement. The spectrophotometric investigation of nitrite concentration was performed utilizing the popular Griess reagent and a reflection-based photometric unit with an organic light emitting diode (OLED) and an organic photodetector (OPD). In this approach a nitrite concentration dependent amount of azo dye is formed, which absorbs light around ~540 nm. The organic devices are designed for sensitive detection of absorption changes caused by the presence of this azo dye without the need of a spectrometer. Using a green emitting TCTA:Ir(mppy)3 OLED (peaking at ~512 nm) and a DMQA:DCV3T OPD with a maximum sensitivity around 530 nm, we successfully demonstrated the operation of the OLED–OPD pair for nitrite sensing with a low limit of detection 46 µg/L (1.0 µM) and a linearity of 99%. The hybrid integration of an OLED and an OPD with 0.5 mm × 0.5 mm device sizes and a gap of 0.9 mm is a first step towards a highly compact, low cost and highly commercially viable PON analytic platform. To our knowledge, this is the first demonstration of a fully organic-semiconductor-based monolithic integrated platform for real-time PON photometric nitrite analysis.
Highlights
Nitrates and nitrites play an essential role for plant growth in agriculture
organic light emitting diode (OLED) and a Dimethyl quinacridone (DMQA):DCV3T organic photodetector (OPD) with a maximum sensitivity around 530 nm, we successfully demonstrated the operation of the OLED–OPD pair for nitrite sensing with a low limit of detection 46 μg/L (1.0 μM) and a linearity of 99%
The realized TCTA:Ir(mppy)3 OLEDs and DMQA:DCV3T OPDs were fabricated on a 25 mm × 25 mm glass substrate with a thickness of 1 mm
Summary
Nitrates and nitrites play an essential role for plant growth in agriculture. They are a major component of inorganic fertilizers [1]. Their high solubility in water results in a critical exceedance of limits in the ground water [2]. Recent studies reported carcinogenic effects, methemoglobinemia, and detrimental effects on the thyroid gland and other organs, associated with the ingestion of high concentrations of nitrate and nitrite due to the high toxicity. Methemoglobin is unable to transport oxygen to the tissues. The detection of nitrite in samples such as water, urine, saliva or blood plasma is crucial and has been reported by many different research groups [4]
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