题 目：Estimation of Surface Recombination Velocity in Thin-Film Solar Cells
报告人：Prof. Ronald Österbacka（Åbo Akademi University, Finland）
内容摘要：Processes taking place at contacts are of particular importance in organic and perovskite solar cells where selective contacts that are able to efficiently collect majority carriers, simultaneously blocking minority carriers, are desired. In this research, a method based on using the Charge Extraction by a Linearly Increasing Voltage (CELIV) technique to determine surface recombination velocities at selective and/or blocking contacts in thin-film devices is presented . The method assumes a single-carrier device, with a semiconductor layer sandwiched between an injecting and a non-injecting contact, and is based on injecting a bias-induced carrier reservoir that accumulates at the non-injecting contact. From the size of the injected charge reservoir, which can be determined using CELIV, the effective surface recombination velocity at the non-injecting contact is obtained. Furthermore, the mobility is found to be overestimated by several orders of magnitude in the case of an Ohmic injecting contact . The shortcomings can be traced back to the underlying assumption of a drift-dominated transport. We show how to make correct estimations of the mobility, using a correction factor that accounts for diffusion.
 O.J. Sandberg, et al., Physical Review Letters 118, 076601 (2017).
 O.J. Sandberg, et al., Applied Physics Letters 110, 153504 (2017).
报告人简介：Prof. Österbacka has published more than 180 papers in major international journals since 1996, with a total of 5009 citations (without self-citations, 19.09.2017), yielding an h-index of 37. The publications include one in Science, four in Physical Review Letters, four in Advanced Materials, 10 in Organic Electronics, 20 in Physical Review, and 12 in Applied Physics Letters. In addition he has three granted patents and several patent applications and has been invited more than 50 times to give invited lectures at international conferences and summer schools since 2006.