They also observed a large increase in the orange/red part of the DLE band and a decrease in the NBE intensity after annealing their samples in air at 600°C, similar to what we report here. The predominance of green emission in the DLE after annealing at 1,000°C could be caused by increased recombination at grain boundaries. Figure 5 clearly shows several individual components, corresponding to different radiative transitions, which vary in selleck inhibitor intensity with the annealing temperature.

Further investigations of this material system could therefore help shed light on the origin of the visible band. Figure 5 PL spectra of ZnO NSs produced via annealing of LBZA NSs in air at 400°C, 600°C, 800°C and 1,000°C. The excitation wavelength was 325 nm and the power density was approximately 3 mW/mm2 for all samples. We also investigated the effect of annealing time on the PL properties. Figure 6 shows spectra normalized to the NBE intensity taken from samples annealed in air at 400°C for 10 s, 10 min, 20 min, 30 min and 60 min. The 10 s sample was removed from the furnace within 10 s after the furnace reached the 400°C setpoint and left to cool down at room temperature. The other

samples were removed from the furnace after a given time and left to cool down in the same manner. Figure 6 shows that C59 wnt order the intensity of the NBE band decreases relative to the DLE band with increasing temperature. This is particularly noticeable between the samples that were annealed for 10 s and 60 min, where the NBE to DLE ratio decreases from 1.329 to 0.073. The 10- and 20-min BIBF 1120 anneals result in very similar spectra (ratios of 0.316

and 0.361, respectively), whilst the 30 min sample shows a slight decrease in the acetylcholine ratio (0.155). It should be noted that the 10-, 20- and 30-min spectra are within the variability observed from different growth batches, where environmental conditions such as ambient humidity at the time of synthesis, anneal and measurement might affect the intensity ratio. This also explains the difference in ratio for the 400°C, 10-min spectra in Figures 5 and 6. However, the difference between the 10-s and 60-min sample is significant. The shape of the DLE band remains the same, which points towards a decrease in the probability of band-to-band recombination, rather than an increase in the concentration of a specific defect. Further work is underway to investigate this effect. SEM analysis showed an increase in particle size with increasing annealing time, from 22 nm for the 10-s sample to 32 nm for the 60-min sample. Figure 6 PL spectra of ZnO NSs produced via annealing of LBZA NSs in air at 400°C. The NSs were annealed for 10 s, 10 min, 20 min, 30 min and 60 min. The spectra were normalized to intensity of the NBE band.