Quasi-Planar Core Based Spiro-Type Hole-Transporting Material for Dopant-Free Perovskite Solar Cells
Hole-transporting material (HTMs) are crucial for obtaining the stability and high efficiency of perovskite solar cells (PSCs). However, the current state-of-the-art n-i-p PSCs relied on the use of 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) exhibit inferior intrinsic and ambient stability due to the p-dopant and hydrophilic Li-TFSI additive. In this study, a new spiro-type HTM with a critical quasi-planar core (Z-W-03) is developed to improve both the thermal and ambient stability of PSCs. The results suggest that the planar carbazole structure effectively passivates the trap states compared to the triphenylamine with a propeller-like conformation in spiro-OMeTAD. This passivation effect leads to the shallower trap states when the quasi-planar HTMs interact with the Pb-dimer. Consequently, the device using Z-W-03 achieves a higher Voc of 1.178 V compared to the spiro-OMeTAD's 1.155 V, resulting in an enhanced efficiency of 24.02 %. In addition, the double-column π–π stacking of Z-W-03 results in high hole mobility (~10−4 cm2 V−1 s−1) even without p-dopant. Moreover, when the surface interface is modified, the undoped Z-W-03 device can achieve an efficiency of nearly 23 %. Compared to the PSCs using spiro-OMeTAD, those with Z-W-03 exhibit enhanced stability under N2 and ambient conditions. This superior performance is attributed to the quasi-planar core structure and the presence of multiple CH/π and π–π intermolecular stacking in Z-W-03. The multiple CH/π and π–π intermolecular contacts of HTMs can improve the hole hopping transport. Therefore, it is imperative to focus on further molecular structure design and optimization of spiro-type HTMs incorporating quasi-planar cores and carbazole moieties for the commercialization of PSCs.
2-s2.0-85206239530
39103975
2024-11-18
63
47
e202411217
REVIEWED
EPFL
Funder | Grant Name | Grant Number | Grant URL |
Ministry of Education in Saudi Arabia | |||
Hong Kong Polytechnic University | |||
École Polytechnique Fédérale de Lausanne | |||
Nazarbayev University | BSRF-1W1A | ||
Key Research and Development Program of Guangzhou City | 20220602JBGS02,526,ZH22017001210130PWC | ||
Shenzhen Science and Technology Program | GJHZ20210705142200003,JCYJ20220530141211025 | ||
Guangdong Basic and Applied Basic Research Foundation | 2022A1515010580,2024A1515011834 | ||