Formation of Al-Doped ZnO Nanotubes via Simultaneous Etching and Doping of H_2O-oxidized ZnO Nanorods for Perovskite Solar Cells

摘要

Recently, Pb-based perovskite solar cells (PSCs) have displayed remarkable development and emerged as the leading candidate for next generation photovoltaic system . Most efficient PSCs are based on TiO_2 as electron-transporting layer (ETL). However, high temperature sintering is a prerequisite to synthesize TiO_2, hindering the application of PSCs in flexible substrates. In our previous work, we demonstrated that ZnO nanorods (NRs) formed by low temperature H2O oxidation can be employed as ETL for PSCs . Herein, we present an innovative and facile technique to design Al-doped ZnO nanotubes (AZO NTs) via simultaneous doping and etching of H_2O-oxidized ZnO nanorods (NRs). One-step spin-coating process of a methanolic AlCl_3 solution on top of the NRs was employed to generate AZO NTs. It can be seen that increased AlCl3 coatings resulted in the gradual transformation of the NRs to full NTs, which simultaneously enhanced the film transmittance. Moreover, the AZO NTs exhibited superior electronic properties compared with undoped ZnO NRs. Thus, it can be expected that these enhanced properties, as well as the larger surface area of AZO NTs, could significantly improve the photovoltaic performance of PSCs through a more efficient electron extraction and suppression of carrier recombination. Consequently, we are now targeting to utilize these films as ETL for PSCs. Finally, our H_2O-oxidized nanostructured ZnO films will pave the way for the design and development of low-temperature solution-processed and flexible PSCs.