{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,17]],"date-time":"2026-05-17T11:41:19Z","timestamp":1779018079833,"version":"3.51.4"},"reference-count":49,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2022,1,25]],"date-time":"2022-01-25T00:00:00Z","timestamp":1643068800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"European Regional Development Fund (EFRE)","award":["LPW-E\/1.2.2\/1303"],"award-info":[{"award-number":["LPW-E\/1.2.2\/1303"]}]},{"name":"European Research Council (ERC) under the European Union\u2019s Horizon 2020 research and innovation programme","award":["899861"],"award-info":[{"award-number":["899861"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this study, we present a highly integrated design of organic optoelectronic devices for Point-of-Need (PON) nitrite (NO2\u2212) 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\u2013OPD pair for nitrite sensing with a low limit of detection 46 \u00b5g\/L (1.0 \u00b5M) and a linearity of 99%. The hybrid integration of an OLED and an OPD with 0.5 mm \u00d7 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.<\/jats:p>","DOI":"10.3390\/s22030910","type":"journal-article","created":{"date-parts":[[2022,1,25]],"date-time":"2022-01-25T21:07:11Z","timestamp":1643144831000},"page":"910","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Monolithic Integrated OLED\u2013OPD Unit for Point-of-Need Nitrite Sensing"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3264-3209","authenticated-orcid":false,"given":"Igor","family":"Titov","sequence":"first","affiliation":[{"name":"Integrated Systems and Photonics, Faculty of Engineering, Kiel University, 24118 Kiel, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Markus","family":"K\u00f6pke","sequence":"additional","affiliation":[{"name":"Integrated Systems and Photonics, Faculty of Engineering, Kiel University, 24118 Kiel, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4234-7833","authenticated-orcid":false,"given":"Martina","family":"Gerken","sequence":"additional","affiliation":[{"name":"Integrated Systems and Photonics, Faculty of Engineering, Kiel University, 24118 Kiel, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,1,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"920","DOI":"10.1100\/tsw.2001.269","article-title":"Nitrogen in the Environment: Sources, Problems, and Management","volume":"1","author":"Follett","year":"2001","journal-title":"Sci. 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