Peiwen Lv

High electron mobility ZnO film for high-performance inverted polymer solar cells

High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm2/(V·s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of JSC, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance.

Intrinsic magnetism of a series of Co substituted ZnO single crystals

Magnetic properties of a series of well-substituted Zn1−xCoxO (x = 0.018,0.036 and 0.05) single crystals were studied. A typical paramagnetic anisotropy property, which strengthens when x decreases, was found. A magnetization step was observed at 2 K when the magnetic field is parallel to the c axis, indicating that paramagnetic anisotropy is the origin of the strong crystal field effect on Co2+ ions in ZnO lattices. The Co2+ single-ion anisotropy parameter 2D is obtained as 7.5 K. The effective moment of Co2+ takes the values 2.7 µB, 1.82 µB, 1.49 µB when x = 0.018, 0.036 and 0.05, revealing that more antiferromagnetic coupling between Co2+ ions arises in the perfect crystal when x increases.