1 Electronic supplementary information Template-free TiO 2 hollow submicrospheres embedded with SnO 2 nanobeans as a versatile scattering layer for dye-sensitized solar cells Chih-Liang Wang, Jin-Yun Liao, Yubao Zhao, and Arumugam Manthiram* Materials Science and Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, USA Fax:1-512-471-7681, Tel: 1-512-471-1791; E-mail: rmanth@mail.utexas.edu (A. Manthiram) Synthesis of SnO 2 SnO 2 was fabricated by a hydrothermal synthesis. In a typical synthesis, a solution of 0.216 g K 2 SnO 3 ·3H 2 O and 1.35 g urea was added into a solution of ethanol and water (1:1) contained in a 100 mL Teflon liner sealed with the autoclave and subjected to heat treatment at 180 o C for 18 h in an oven. After washing with ethanol and water, the SnO 2 powder was heated at 500 o C for 3 h air. Synthesis of TiO 2 hollow submicrospheres The TiO 2 hollow submicrospheres were fabricated with a facile template-free solvothermal synthesis. 1 In a typical synthesis of TiO 2 hollow submicrospheres, a solution containing tetra-n- butyl titanate (2.33 mmol), ethanedioic acid (0.013 mol), and isopropyl alcohol (66.67 mL) was dropped in a 100 mL Teflon liner sealed with the autoclave and subjected to heat treatment at 180 o C for 6 h in an oven. Subsequently, the TiO 2 hollow submicrospheres after washing with ethanol and water several times were collected and dried for 5 h at 100 o C in a vacuum oven. The powder was heated at 500 o C for 3 h under air atmosphere before preparing the paste for doctor blade coating. Electronic Supplementary Material (ESI) for ChemComm. This journal is © The Royal Society of Chemistry 2015