Lai Lai-Hung, Gomulya Widianta, Protesescu Loredana, Kovalenko Maksym V, Loi Maria A
Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen, 9747 AG, The Netherlands.
Phys Chem Chem Phys. 2014 Apr 28;16(16):7531-7. doi: 10.1039/c4cp00632a.
We report on the fabrication of CdSe quantum dot (QD) sensitized electrodes by direct adsorption of colloidal QDs on mesoporous TiO2 followed by 3-mercaptopropionic acid (MPA) ligand exchange. High efficiency photoelectrochemical hydrogen generation is demonstrated by means of these electrodes. The deposition of ZnS on TiO2/CdSe further improves the external quantum efficiency from 63% to 85% at 440 nm under -0.5 V vs. SCE. Using the same photoelectrodes, solar cells with the internal quantum efficiency approaching 100% are fabricated. The ZnS deposition increases the photocurrent and chemical stability of the electrodes. Investigation of the carrier dynamics of the solar cells shows that ZnS enhances the exciton separation rate in CdSe nanocrystals, which we ascribe to the formation of a type II heterojunction between ZnS and CdSe QDs. This finding is confirmed by the dynamics of the CdSe photoluminescence, which in the presence of ZnS becomes noticeably faster.
我们报道了通过将胶体量子点直接吸附在介孔二氧化钛上，随后进行3-巯基丙酸（MPA）配体交换来制备CdSe量子点（QD）敏化电极的方法。通过这些电极展示了高效的光电化学产氢。在相对于饱和甘汞电极（SCE）为-0.5 V的条件下，在TiO2/CdSe上沉积ZnS进一步将440 nm处的外量子效率从63%提高到85%。使用相同的光电极，制备了内量子效率接近100%的太阳能电池。ZnS的沉积提高了电极的光电流和化学稳定性。对太阳能电池载流子动力学的研究表明，ZnS提高了CdSe纳米晶体中的激子分离率，我们将其归因于ZnS和CdSe量子点之间形成了II型异质结。CdSe光致发光的动力学证实了这一发现，在存在ZnS的情况下，其明显加快。
