Solution processed thin films of Nb-doped TiO2 nanoparticles as hole blocking layer for organic solar cells

Wonmok Lee, Incheol Kim, Ilwoo Ok, Dahee Ahn, Hyunjung Lee, Jin Ho Kim, Kyungkon Kim

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


In this study, Nb-doped TiO2 nanoparticles were synthesized by sol-gel method with controlled doping ratios up to 6 mol%. Catalyzed by p-toluene sulfonic acid, alkoxide precursors of Ti and Ni were stabilized by acetylacetone ligand, and converted to the organically modified nanoparticles which were well dispersible in alcohols. Transmission electron microscopy and X-ray diffraction measurements revealed that TiO2 nanoparticle possesses anatase morphologies, and the doping ratios were confirmed by X-ray photoelectron spectroscopy. Uniform thin films of Nb-doped TiO2 were obtained by spin coating dilute alcohol dispersions of Nb-doped nanoparticles. Ellipsometric characterizations were carried out for the as-coated film and the sintered film as well to characterize the indices of refraction, and atomic force microscopy showed subnanometer-scale roughness of Nb-doped films. Owing to the improved roughness via doping, Nb-doped TiO2 thin films exhibited enhanced solar cell efficiencies when used as hole-blocking layer of organic hetero-junction solar cell.

Original languageEnglish
Pages (from-to)161-165
Number of pages5
JournalThin Solid Films
StatePublished - 28 Feb 2014

Bibliographical note

Funding Information:
Authors thank H. Park in Kookmin University for measuring film resistance. W. Lee gratefully acknowledges the support by the Center for Electro-Photo Behaviors in Advanced Molecular Systems at POSTECH (No. 2012-0000532 ). K. Kim acknowledges the New & Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Knowledge Economy ( 2012T100100054 ). H. Lee acknowledges the financial support by the National Research Foundation of Korea grant funded by the Korean Government (MEST) ( NRF-2012R1A2A2A01014288 ).


  • Hole-blocking layer
  • Nb-doped TiO nanoparticles
  • Organic hetero-junction solar cell
  • Organically modified
  • Sol-gel method
  • Thin film


Dive into the research topics of 'Solution processed thin films of Nb-doped TiO2 nanoparticles as hole blocking layer for organic solar cells'. Together they form a unique fingerprint.

Cite this