@article { ISI:000485015600002,
	title = {Dopant-free Spiro-OMeTAD as hole transporting layer for stable and efficient perovskite solar cells},
	journal = {ORGANIC ELECTRONICS},
	volume = {74},
	year = {2019},
	month = {NOV},
	pages = {7-12},
	abstract = {High efficiency organic-inorganic hybrid perovskite solar cells have attracted significant attention and experienced a rapid development in recent years. Lithium-doped spiro-OMeTAD is one of the most commonly used hole transporting material, however, the hygroscopicity of lithium dopant usually causes serious moisture instability of devices. Herein, we demonstrate a dopant-free spiro-OMeTAD as hole transporting layer to improve the ambient stability of planar perovskite solar cells. With the optimization of the thickness of spiro-OMeTAD layer, the dopant-free spiro-OMeTAD based device achieved a comparable device performance with a champion power conversion efficiency of 16.92\%. Moreover, the unencapsulated dopant-free device showed significantly improved stability, which still maintained 95\% of its initial efficiency after storage in ambient environment for 60 days. This work provides a simple and valid approach to overcome the instability issue of spiro-OMeTAD based devices, paving a way to manufacture more stable and efficient perovskite photovoltaics.},
	issn = {1566-1199},
	doi = {10.1016/j.orgel.2019.06.039},
	author = {Luo, Wei and Wu, Cuncun and Wang, Duo and Zhang, Zehao and Qi, Xin and Guo, Xuan and Qu, Bo and Xiao, Lixin and Chen, Zhijian}
}
