ZnO layers doped with small molecule viologen derivatives, i.e., 1,1 0 -bis(4hydroxypropyl)-[4,4 0 -bipyridine]-1,1 0 -diium bromide (V─OH) or 1,1 0 -bis(2,3dihydroxypropyl)-[4,4 0 -bipyridine]-1,1 0 -diium bromide (V─2OH), are prepared and used as the electron transport layer in inverted polymer solar cells (iPSCs). The presence of V─OH (or V─2OH) in ZnO layer and the formation of homogeneous V─OH (or V─2OH) doped ZnO layer are confirmed by Xray photoelectron spectroscopy. The electron mobilities of doped ZnO layers are comparable to those of pristine ZnO because the crystallinity of the ZnO layer is not significantly affected by the doping process. Kelvin probe microscopy measurements show that the work function of doped ZnO layers is in the range of À4.2 -À4.3 eV, which is higher than that of pristine ZnO (À4.5 eV). This is due to the formation of interface dipoles at the interface between the ZnO layer and the active layer. The water contact angle data reflect the existence of quaternary ammonium bromide on the surface, and unreacted hydroxyl groups are pointed away from the surface of the ZnO layer. iPSCs based on V─OH doped ZnO and V─2OH doped ZnO exhibit power conversion efficiencies (PCEs) up to 9.0% and 8.6%, which are dramatically enhanced compared to the device based on pristine ZnO (PCE ¼ 7.4%).

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Commercial silica gel only used once by many researchers and affected high cost for purification process, also less support the green chemistry program. This research focused in regeneration silica gel that used purification of temulawak's extracts (Curcuma xanthorrhiza Roxb) by vacuum column chromatography. Sample extracts (contains 10.1195±0.5971% of curcuminoids) was purified by vacuum column chromatography (pressure: 45 kPa, column: 100mm on length and 16mm on diameter). Ethanol 96% and acetone were compared as eluent. The amount of solvent and yield of curcuminoids used as indicator purification. The silica gel was regenerated with heating in 600°C for 8 hours The silica gels were analyzed by IR spectroscopy and X-ray diffraction. Furthermore, regenerated silica gel was used as the stationary phase in vacuum column chromatography under the same conditions with the previous purification. All the purification experiments were performed in three repetitions. Based on regression equation, y=0.132x+0.0011 (r 2 =0.9997) the yield of curcuminoids on purified products using ethanol as the eluent was improved 4.26% (to 14.3724±0.5749%) and by acetone was improved 3,03% (to 13.1450 ±0.6318%). The IR spectrum of both silica gel showed the same vibration profile and also there were three crystallinity peaks missing on its X-ray diffraction. Regenerated silica gel has the same performance with new silica gel in purification of temulawak's extract: by ethanol has increased 4.08% (14.1947±0.7415%) and 2.93% (13.0447±0.4822) by acetone. In addition, all purification products showed similar TLC profiles. Purification using regenerated silica gel as the adsorbent on vacuum column chromatography has exactly same potential with the new silica gel.