Strong Anisotropy and Piezo-Phototronic Effect in SnO2 Microwires

1D microwires with low-symmetric crystal structures are promising platforms to realize the anisotropy and piezotronics, enabling diverse novel device functions such as polarization sensitive photodetection, strain sensing, and energy conversion. Here, the highly anisotropy with polarized Raman spectra and angle-resolved photocurrent as well as the remarkable piezoelectric characteristics in the 1D tin dioxide (SnO2) microwires is reported for the first time. The gauge factor can reach as high as 4100, implying the great strain "gating" effect on the current modulation. The cyclic stretching and releasing of the microwires has led to the significant oscillating piezoelectric current outputs of 750 pA. Moreover, the ultraviolent photoresponse is dramatically improved by one order of magnitude with fast speed of 2 ms benefitting from the excellent piezo-phototronic effect. Both highly anisotropy and superior piezoelectricity in this work have opened up the new application scenarios of SnO2 microwires in unique angle-dependent and stretchable electronics and optoelectronics.