Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Adv Mater. 2017 Jul;29(26). doi: 10.1002/adma.201700607. Epub 2017 May 3.
Efficient wide-bandgap (WBG) perovskite solar cells are needed to boost the efficiency of silicon solar cells to beyond Schottky-Queisser limit, but they suffer from a larger open circuit voltage (V ) deficit than narrower bandgap ones. Here, it is shown that one major limitation of V in WBG perovskite solar cells comes from the nonmatched energy levels of charge transport layers. Indene-C60 bisadduct (ICBA) with higher-lying lowest-unoccupied-molecular-orbital is needed for WBG perovskite solar cells, while its energy-disorder needs to be minimized before a larger V can be observed. A simple method is applied to reduce the energy disorder by isolating isomer ICBA-tran3 from the as-synthesized ICBA-mixture. WBG perovskite solar cells with ICBA-tran3 show enhanced V by 60 mV, reduced V deficit of 0.5 V, and then a record stabilized power conversion efficiency of 18.5%. This work points out the importance of matching the charge transport layers in perovskite solar cells when the perovskites have a different composition and energy levels.
高效的宽能隙 (WBG) 钙钛矿太阳能电池对于将硅太阳能电池的效率提升至肖特基-奎塞尔极限以上是必要的，但它们的开路电压 (V ) 损失比能隙较窄的钙钛矿太阳能电池更大。在这里，研究表明 WBG 钙钛矿太阳能电池中 V 的一个主要限制来自于电荷传输层的能级不匹配。对于 WBG 钙钛矿太阳能电池，需要具有更高的最低未占据分子轨道能级的茚并-C60 双加成物 (ICBA)，但在观察到更大的 V 之前，需要最小化其能量无序性。通过从合成的 ICBA 混合物中分离出异构体 ICBA-tran3，应用一种简单的方法来降低能量无序性。用 ICBA-tran3 制成的 WBG 钙钛矿太阳能电池的 V 提高了 60 mV，V 损失减少了 0.5 V，然后稳定的功率转换效率达到了创纪录的 18.5%。这项工作指出了当钙钛矿具有不同的组成和能级时，在钙钛矿太阳能电池中匹配电荷传输层的重要性。
