Abstract
AbstractA novel biphenyl fumaronitrile as an acceptor and triphenylamine as donor conjugated building blocks are used for the first time to successfully synthesize donor–acceptor–donor molecule (D‐A‐D) 2,3‐bis(4′‐(bis(4‐methoxyphenyl)amino)‐[1,1′‐biphenyl]‐4‐yl)fumaronitrile (TPA‐BPFN‐TPA). The new TPA‐BPFN‐TPA with low‐lying HOMO is used as a dopant‐free hole‐transporting material (HTM) in mesoporous perovskite solar cells. The performance of the solar cells using this new HTM is compared with the traditional 2,2′,7,7′‐tetrakis(N,N′‐di‐p‐methoxyphenylamino)‐ 9,9′‐spirobifluorene (Spiro‐OMeTAD) HTM based devices for outdoor and indoor performance evaluation. Under 1 sun illumination, dopant‐free TPA‐BPFN‐TPA HTM based devices exhibit a power conversion efficiency (PCE) of 18.4%, which is the record efficiency to date among D‐A‐D molecular design based dopant‐free HTMs. Moreover, the stability of unencapsulated TPA‐BPFN‐TPA‐based devices shows improvement over Spiro‐OMeTAD‐based devices in harsh relative humidity condition of 70%. Another exciting feature of the newly developed HTM is that the TPA‐BPFN‐TPA‐based devices exhibit improved PCE of 30% and 20.1% at 1000 lux and 200 lux illuminations, respectively. This new finding provides a solution to fabricate low indoor (low light) and outdoor (1 sun) perovskite solar cell devices with high efficiency for cutting‐edge energy harvesting technology.
Highlights
On account of the global climate change and issues related to energy security, technologies relying on renewable non-fossil energy resources are in demand
We have demonstrated for the first time the effect of changing dopant-free donor–acceptor–donor molecule (D-A-D) hole-transporting material (HTM)/mesoporous perovskite interface on the performance of perovskite solar cells (PSCs) under low light illumination for indoor application or application of mesoporous solar cells in low insolation regions or weather conditions
We have successfully designed and synthesized a new BPFN core based TPA-BPFN-TPA hole-transport material which is employed without the addition of hygroscopic additives (e.g., LiTFSI) in a mesoporous perovskite architecture yielding a record efficiency of 18.4%, which is higher than that of doped standard Spiro-OMeTAD under 1 sun condition
Summary
On account of the global climate change and issues related to energy security, technologies relying on renewable non-fossil energy resources are in demand. While several D-A-D HTMs fabricated in PSCs have been reported,[10,20,21,22,23,24] this is the first report of a novel dopant-free D-A-D-based HTM for indoor application with such impressive efficiency using low-cost materials and device technology
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