Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
Nanoscale. 2017 Sep 14;9(35):12916-12924. doi: 10.1039/c7nr04026a.
Hole transporting materials (HTMs) play an important role in most efficient perovskite solar cells (PSCs). In particular, donor-π-bridge-donor type oligomers (D-π-D) have been explored extensively as alternative and economical HTMs. In the present work, a series of triphenylamine-based derivatives as alternatives to the expensive Spiro-OMeTAD were explored by using first-principles calculations combined with the Marcus theory. The electronic structures, optical properties and hole mobilities of all the molecules were investigated to reveal the relationship between their charge-transport properties and the π-bridge conjugation. The HOMO levels decrease with the extension of the π-bridge conjugation length, which may lead to higher open-circuit voltages. Moreover, we employed a quantum mechanical (QM) methodology to estimate the carrier mobility for organic crystals. Specifically, an orientation function μ (V, λ, r, θ, γ; Φ) is first applied to quantitatively evaluate the overall carrier mobility of HTMs in PSCs. The theoretically calculated results validate that this model predicts the hole mobility of HTMs correctly. More importantly, it is revealed that enhancing the π-bridge conjugation in HTMs can improve the hole mobility, which will definitely improve the performance of PSCs. We hope that our theoretical investigation will offer a reliable calculation method to estimate the charge-transport properties of novel HTMs applied in perovskite solar cells.
空穴传输材料（HTMs）在大多数高效钙钛矿太阳能电池（PSCs）中起着重要作用。特别是，供体-π-桥-供体型低聚物（D-π-D）已被广泛探索作为替代和经济的 HTMs。在本工作中，通过使用第一性原理计算结合 Marcus 理论，探索了一系列取代昂贵的 Spiro-OMeTAD 的三苯胺基衍生物。研究了所有分子的电子结构、光学性质和空穴迁移率，以揭示它们的电荷传输性质与π-桥共轭之间的关系。HOMO 能级随π-桥共轭长度的增加而降低，这可能导致更高的开路电压。此外，我们采用量子力学（QM）方法来估计有机晶体的载流子迁移率。具体来说，首先应用取向函数μ（V，λ，r，θ，γ；Φ）来定量评估 PSCS 中 HTMs 的整体载流子迁移率。理论计算结果验证了该模型能够正确预测 HTMs 的空穴迁移率。更重要的是，揭示了增强 HTMs 中的π-桥共轭可以提高空穴迁移率，这肯定会提高 PSCs 的性能。我们希望我们的理论研究将为估计应用于钙钛矿太阳能电池的新型 HTMs 的电荷传输性质提供一种可靠的计算方法。
