Koleilat Ghada I, Levina Larissa, Shukla Harnik, Myrskog Stefan H, Hinds Sean, Pattantyus-Abraham Andras G, Sargent Edward H
Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4, Canada.
ACS Nano. 2008 May;2(5):833-40. doi: 10.1021/nn800093v.
Half of the sun's power lies in the infrared. As a result, the optimal bandgaps for solar cells in both the single-junction and even the tandem architectures lie beyond 850 nm. However, progress in low-cost, large-area, physically flexible solar cells has instead been made in organic and polymer materials possessing absorption onsets in the visible. Recent advances have been achieved in solution-cast infrared photovoltaics through the use of colloidal quantum dots. Here we report stable solution-processed photovoltaic devices having 3.6% power conversion efficiency in the infrared. The use of a strongly bound bidentate linker, benzenedithiol, ensures device stability over weeks. The devices reach external quantum efficiencies of 46% in the infrared and 70% across the visible. We investigate in detail the physical mechanisms underlying the operation of this class of device. In contrast with drift-dominated behavior in recent reports of PbS quantum dot photovoltaics, we find that diffusion of electrons and holes over hundreds of nanometers through our PbSe colloidal quantum dot solid is chiefly responsible for the high external quantum efficiencies obtained in this new class of devices.
太阳能量的一半处于红外波段。因此，无论是单结结构还是串联结构的太阳能电池，其最佳带隙都在850纳米以上。然而，低成本、大面积、物理柔性的太阳能电池的进展却是在可见光范围内具有吸收起始点的有机和聚合物材料方面取得的。通过使用胶体量子点，溶液浇铸红外光伏技术最近取得了进展。在此，我们报告了在红外波段功率转换效率达3.6%的稳定的溶液处理光伏器件。使用强键合双齿连接体苯二硫醇可确保器件在数周内保持稳定。这些器件在红外波段的外量子效率达到46%，在可见光范围内达到70%。我们详细研究了这类器件工作的物理机制。与最近关于硫化铅量子点光伏器件的报告中以漂移为主的行为不同，我们发现电子和空穴在我们的硒化铅胶体量子点固体中扩散数百纳米是这类新器件获得高外量子效率的主要原因。
