Growth of dandelion-shaped CuInSe2 nanostructures by a two-step solvothermal process

Abstract

CuInSe2 (CIS) nanodandelion structures were synthesized by a two-step solvothermal approach. First, InSe nanodandelions were prepared by reacting In(acac)3 with trioctylphosphine-selenide (TOP-Se) in 1-octadecene (ODE) at 170 °C in the presence of oleic acid. These InSe dandelions were composed of polycrystalline nanosheets with thickness < 10 nm. The size of the InSe dandelions could be tuned within the range of 300 nm–2 µm by adjusting the amount of oleic acid added during the synthesis. The InSe dandelion structures were then reacted with Cu(acac)2 in the second-step solvothermal process in ODE to form CIS nanodandelions. The band gap of the CIS dandelions was determined from ultraviolet (UV) absorption measurements to be ~ 1.36 eV, and this value did not show any obvious change upon varying the size of the CIS dandelions. Brunauer–Emmett–Teller (BET) measurements showed that the specific surface area of these CIS dandelion structures was 44.80 m2 g − 1, which was more than five times higher than that of the CIS quantum dots (e.g. 8.22 m2 g − 1) prepared by using reported protocols. A fast photoresponsive behavior was demonstrated in a photoswitching device using the 200 nm CIS dandelions as the active materials, which suggested their possible application in optoelectronic devices.