One-step synthesis of porous transparent conductive oxides by hierarchical self-assembly of aluminum-doped ZnO nanoparticles

Renheng Bo, Fan Zhang, Shulin Bu, Noushin Nasiri, Iolanda Di Bernardo, Thanh Tran-Phu, Aabhash Shrestha, Hongjun Chen, Mahdiar Taheri, Shuhua Qi, Yi Zhang, Hemant Kumar Mulmudi, Josh Lipton-Duffin, Enrico Della Gaspera, Antonio Tricoli*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


Transparent conductive oxides (TCOs) are highly desirable for numerous applications ranging from photovoltaics to light-emitting diodes and photoelectrochemical devices. Despite progress, it remains challenging to fabricate porous TCOs (pTCOs) that may provide, for instance, a hierarchical nanostructured morphology for the separation of photoexcited hole/electron couples. Here, we present a facile process for the fabrication of porous architectures of aluminum-doped zinc oxide (AZO), a low-cost and earth-abundant transparent conductive oxide. Three-dimensional nanostructured films of AZO with tunable porosities from 10 to 98% were rapidly self-assembled from flame-made nanoparticle aerosols. Successful Al doping was confirmed by X-ray photoemission spectroscopy, high-resolution transmission electron microscopy, elemental mapping, X-ray diffraction, and Fourier transform infrared spectroscopy. An optimal Al-doping level of 1% was found to induce the highest material conductivity, while a higher amount led to partial segregation and formation of aluminum oxide domains. A controllable semiconducting to conducting behavior with a resistivity change of more than 4 orders of magnitudes from about 3 × 102 to 9.4 × 106 Ω cm was observed by increasing the AZO film porosity from 10 to 98%. While the denser AZO morphologies may find immediate application as transparent electrodes, we demonstrate that the ultraporous semiconducting layers have potential as a light-driven gas sensor, showing a high response of 1.92–1 ppm of ethanol at room temperature. We believe that these tunable porous transparent conductive oxides and their scalable fabrication method may provide a highly performing material for future optoelectronic devices.
Original languageEnglish
Pages (from-to)9589-9599
Number of pages11
JournalACS Applied Materials and Interfaces
Issue number8
Publication statusPublished - 26 Feb 2020


  • porous transparent conductive oxides
  • one-step synthesis
  • aluminum-doped zinc oxide (AZO)
  • optoelectronics
  • sensing


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