Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford OX1 3PU, United Kingdom.
Nano Lett. 2014 Jun 11;14(6):3247-54. doi: 10.1021/nl500627x. Epub 2014 May 7.
Organic-inorganic halide perovskites, such as CH3NH3PbX3 (X = I(-), Br(-), Cl(-)), are attracting growing interest to prepare low-cost solar cells that are capable of converting sunlight to electricity at the highest efficiencies. Despite negligible effort on enhancing materials' purity or passivation of surfaces, high efficiencies have already been achieved. Here, we show that trap states at the perovskite surface generate charge accumulation and consequent recombination losses in working solar cells. We identify that undercoordinated iodine ions within the perovskite structure are responsible and make use of supramolecular halogen bond complexation to successfully passivate these sites. Following this strategy, we demonstrate solar cells with maximum power conversion efficiency of 15.7% and stable power output over 15% under constant 0.81 V forward bias in simulated full sunlight. The surface passivation introduces an important direction for future progress in perovskite solar cells.
有机-无机卤化物钙钛矿，如 CH3NH3PbX3（X = I(-), Br(-), Cl(-)），正吸引着越来越多的关注，用于制备能够以最高效率将阳光转化为电能的低成本太阳能电池。尽管在提高材料纯度或钝化表面方面几乎没有付出任何努力，但已经实现了高效率。在这里，我们表明钙钛矿表面的陷阱态会在工作太阳能电池中产生电荷积累和随后的复合损耗。我们确定了钙钛矿结构中配位不足的碘离子是造成这种情况的原因，并利用超分子卤键络合成功地对这些位点进行了钝化。通过这种策略，我们展示了太阳能电池，其最大功率转换效率为 15.7%，在模拟全阳光下以 0.81 V 的恒定正向偏压稳定输出超过 15%的功率。表面钝化为钙钛矿太阳能电池的未来发展提供了一个重要方向。
