This version is available at https://strathprints.strath.ac.uk/44172/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Abstract: Two formats of all-organic distributed-feedback lasers with improved photostability, respectively called nanocomposite and encapsulated lasers, are reported. These lasers are compatible with mechanically-flexible platforms and were entirely fabricated using softlithography and spin-coating techniques. The gain elements in both types of lasers were monodisperse -conjugated star-shaped macromolecules (oligofluorene truxene, T3). In the nanocomposites lasers, these elements were incorporated into a transparent polyimide matrix, while in the encapsulated devices a neat layer of T3 was overcoated with Poly(vinyl alcohol) (PVA). The T3-nanocomposite devices demonstrated a 1/e degradation energy dosage up to ~27.0 ± 6.5 J/cm 2 with a threshold fluence of 115 ± 10 µJ/cm 2 . This represents a 3-fold improvement in operation lifetime under ambient conditions compared to the equivalent laser made with neat organic films, albeit with a 1.6-time increase in threshold. The PVA-encapsulated lasers showed the best overall performance: a 40-time improvement in the operation lifetime and crucially no-trade-off on the threshold, with respectively a degradation energy dosage of ~280 ± 20 J/cm 2 and a threshold fluence of 36 ± 8 µJ/cm 2 .© 2013 Optical Society of America , 1985). 17. W. Zhao, T. Cao, and J. M. White, "On the origin of green emission in polyfluorene polymers: the roles of thermal oxidation degradation and crosslinking," Adv. Funct. Mater. 14(8), 783-790 (2004). 18. L. Cerdán, A. Costela, G. Durán-Sampedro, I. García-Moreno, M. Calle, M. Juan-y-Seva, J. de Abajo, and G. A.Turnbull, "New perylene-doped polymeric thin films for efficient and long-lasting lasers," J. Mater. Chem. Immergut, and E. A. Grulke, Polymer Handbook (Wiley, 1999). 32. J. Chilwell and I. Hodgkinson, "Thin-films field-transfer matrix theory of planar multilayer waveguides and reflection from prism-loaded waveguides," J. Opt. Soc. Am. 1(7), 742-753 (1984). 33. S. Riechel, U. Lemmer, J. Feldmann, S. Berleb, A. G. Mückl, W. Brütting, A. Gombert, and V. Wittwer, "Very compact tunable solid-state laser utilizing a thin-film organic semiconductor," Opt. Lett. 26(9), 593-595 (2001). 34. M. Lu, B. T. Cunningham, S.-J. Park...