Picture of boy being examining by doctor at a tuberculosis sanatorium

Understanding our future through Open Access research about our past...

Strathprints makes available scholarly Open Access content by researchers in the Centre for the Social History of Health & Healthcare (CSHHH), based within the School of Humanities, and considered Scotland's leading centre for the history of health and medicine.

Research at CSHHH explores the modern world since 1800 in locations as diverse as the UK, Asia, Africa, North America, and Europe. Areas of specialism include contraception and sexuality; family health and medical services; occupational health and medicine; disability; the history of psychiatry; conflict and warfare; and, drugs, pharmaceuticals and intoxicants.

Explore the Open Access research of the Centre for the Social History of Health and Healthcare. Or explore all of Strathclyde's Open Access research...

Image: Heart of England NHS Foundation Trust. Wellcome Collection - CC-BY.

Ultralow-threshold up-converted lasing in oligofluorenes with tailored strong nonlinear absorption

Guzelturk, Burak and Kanibolotsky, Alexander L. and Orofino-Pena, Clara and Laurand, Nicolas and Dawson, Martin D. and Skabara, Peter and Demir, Hilmi Volkan (2015) Ultralow-threshold up-converted lasing in oligofluorenes with tailored strong nonlinear absorption. Journal of Materials Chemistry. C, 3 (46). pp. 12018-12025. ISSN 2050-7526

[img]
Preview
Text (Guzelturk-etal-JMCC-2015-Ultralow-threshold-up-converted-lasing-in-oligofluorenes-with-tailored)
Guzelturk_etal_JMCC_2015_Ultralow_threshold_up_converted_lasing_in_oligofluorenes_with_tailored.pdf
Accepted Author Manuscript

Download (1MB) | Preview

Abstract

Nonlinear optical response in organic semiconductors has been an attractive property for many practical applications. For frequency up-converter lasers, to date, conjugated polymers, fluorescent dyes and small organic molecules have been proposed but their performances have been severely limited due to the difficulty of simultaneously achieving strong nonlinear optical response and high performance optical gain. In this work, we show that structurally designed truxene-based star-shaped oligofluorenes exhibit strong structure-property relationships enabling enhanced nonlinear optical response with favorable optical gain performance. As the number of fluorene repeat units in each arm is increased from 3 to 6, these molecules demonstrate a two-photon absorption cross-section as high as 2200 GM, which is comparable to that of linear conjugated polymers. Tailored truxene oligomers with six fluorene units in each arm (T6) show two-photon absorption pumped amplified spontaneous emission with a threshold as low as 2.43 mJ/cm2, which is better than that of the lowest reported threshold in organic semiconductors. Furthermore, we show a frequency up-converted laser using the newly designed and synthesized star-shaped oligomer T6 with a threshold as low as 3.1 mJ/cm2, which is more than an order of magnitude lower than that of any conjugated polymer. Thus, these oligomers with enhanced nonlinear optical properties are highly attractive for bio-integrated applications such as photodynamic therapy and in-vivo bio-sensing.