Effect of BCP buffer layer on eliminating charge accumulation for high performance of inverted perovskite solar cells
Effect of BCP buffer layer on eliminating charge accumulation for high performance of inverted perovskite solar cells
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BCP缓冲层对消除电荷积累以实现高性能倒置钙钛矿太阳能电池的影响
DOI：
10.1039/c7ra06365b
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发表时间：
2017-01-01
期刊：
影响因子：
3.9
通讯作者：
Chen, Wei
中科院分区：
文献类型：
--
作者：
Chen, Chuanliang;Zhang, Shasha;Chen, Wei
浴铜灵（BCP）缓冲层常用于高性能的反型钙钛矿太阳能电池（PSCs）中，但其工作机制尚未完全阐明。在此，通过热蒸发沉积不同厚度的BCP层制备了一系列器件。借助单二极管模型对电流 - 电压（J - V）数据进行拟合，确定了BCP层厚度对器件性能的影响。由于形成了欧姆接触并减少了界面电荷复合，临界BCP厚度为5nm的器件获得了高达17.9%的最佳功率转换效率（PCE）。然而，如果BCP层太薄或太厚，由于不同的机制会出现电荷积累，导致器件性能下降，这通过电容 - 电压（C - V）特性在光照下某一偏压区域出现峰值电容得到了明确证实。在PCBM和Ag之间插入这种临界厚度的薄BCP层还提高了器件的长期稳定性，其T - 80寿命在环境空气中从约6小时增加到约50小时。这项工作为通过缓冲层优化提高钙钛矿太阳能电池的性能提供了见解，并且电容 - 电压特性的测量为检测与电荷积累相关的光伏器件缺陷提供了新的线索。
Bathocuproine (BCP) buffer layer has been commonly used in inverted p-i-n perovskite solar cells (PSCs) for high performance, but its working mechanism has not been thoroughly elucidated. Here, a series of devices have been fabricated with controlled thicknesses of BCP layers deposited by thermal evaporation. With the aid of J-V data fitting by a single-diode model, the effect of BCP layer thickness on the device performance has been identified. An optimal power conversion efficiency (PCE) up to 17.9% has been obtained for the device with a critical BCP thickness of 5 nm, thanks to the formation of ohmic contact and reduction of interfacial charge recombination. While if the BCP layer is too thin or too thick, charge accumulation will emerge due to different mechanisms and lead to device performance degradation, which have been clearly confirmed by capacitance-voltage (C-V) characteristic displaying a peak capacitance at a certain bias region under illumination. The insertion of such a critical thin BCP layer between PCBM and Ag also resulted in long-term stability improvement of the devices, of which the T-80 lifetime increased from similar to 6 hours to similar to 50 hours in ambient air. This work gives insight into improving PSCs' performance through buffer layer's optimization, and the measurement of C-V characteristic provides a new clue to detect the defection of photovoltaic device associated with charge accumulation.