Ezhumalai Y.Lee B.Fan M.-S.Harutyunyan B.Prabakaran K.Lee C.-P.Chang S.H.Ni J.-S.Vegiraju S.Priyanka P.Wu Y.-W.Liu C.-W.Yau S.Lin J.T.Wu C.-G.Bedzyk M.J.Chang R.P.H.Chen M.-C.Ho K.-C.Marks T.J.2019-05-172019-05-17201720507488https://scholars.lib.ntu.edu.tw/handle/123456789/408705A new series of metal-free alkylated tetrathienoacene (TTAR)-based organic chromophores, TPA-TTAR-TA (R = branched-C8H17, 1, TTAR-b8; R = C15H31, 2, TTAR-15; R = C9H19, 3, TTAR-9), are synthesized for application in dye-sensitized solar cells (DSSCs). Due to the extensively conjugated TTAR £k-bridge, all three dyes exhibit high extinction coefficients (1 ¡Ñ 105 M-1 cm-1). By systematically exploring the effects of the TTAR alkyl chain substituents, a significant influence of the dye coverage (orientation) on the TiO2 surfaces is observed. The branched-alkyl TTAR-b8 (1) promotes significant tilting and packing distortion on TiO2 in comparison to more ordered monolayers of linear long alkyls TTAR-15 (2) and TTAR-9 (3). Photophysical measurements on the dye-grafted TiO2 films reveal that the branched-alkylated TTA unit in 1 enhances the electron injection efficiency, in agreement with the high quantum efficiency. Notably, by utilizing a three-dimensional (3D) photonic crystal (PhC) layer to enhance the coherent scattering an increase the light absorption, TTAR-b8 exhibits higher short-circuit current densities and achieved a high PCE of 11.18%. TTAR-b8 is thus the best performing fused-thiophene-based organic DSSC dye reported to date. ? 2017 The Royal Society of Chemistry.journal article10.1039/c7ta01825h2-s2.0-85021661054https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021661054&doi=10.1039%2fc7ta01825h&partnerID=40&md5=4ec0215f50482d66e86af5ad18b65247