非富勒烯体异质结有机太阳能电池的 N 掺杂增强了光生和激子离解,Journal of Materials Chemistry A

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非富勒烯体异质结有机太阳能电池的 N 掺杂增强了光生和激子离解
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2022-08-15 , DOI: 10.1039/d2ta05078a
Jiaqi Xie ₁ , Weihua Lin ₂ , Guillermo C. Bazan ₃ , Tõnu Pullerits ₂ , Kaibo Zheng _{2,

4} , Ziqi Liang ₁

Affiliation

非富勒烯有机太阳能电池中体异质结层的N型掺杂可以通过填充陷阱和优化电子路径来有效改善劣质电子传输，从而更好地平衡器件中的电荷传输。然而，这种机制提供了对更强的光产生、长寿命的激子以及同时增加的短路电流密度 ( J _SC ) 和开路电压 ( V _OC ) 的不完全理解，这些也受益于 n 型掺杂。在这里，我们研究了分子 n 型掺杂剂如何影响基于非富勒烯的共混物中的光学特性、分子间堆积行为、电荷载流子动力学和光伏性能。当加入原型 n 型掺杂剂时N -DMBI 加入基准 PM6:Y6 混合物中，促进了 PM6/Y6 的结晶，延长了晶体相干长度，这与光吸收增强有关。N掺杂通过扩张间隙、减少陷阱态和降低激子结合能来延缓供体/受体 (D/A) 界面和组成域内的萌发重组 (GR) 来延长激子寿命。尽管由于掺杂剂嵌入而在扩大的 D/A 间隙中的界面电荷转移较慢，但由于受阻的界面 GR，激子离解仍然非常有效。因此，冠军在最优N处反转单元格-DMBI 含量可提供 15.34% 的可观效率，这是最先进的基于 PM6:Y6 的类似二元电池中最高的。与未掺杂器件相比，这种改进主要归因于J _SC（高达 26.41 mA cm ^-2）和V _OC（高达 0.86 V）的同时增加。

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N-doping of nonfullerene bulk-heterojunction organic solar cells strengthens photogeneration and exciton dissociation

N-type doping of the bulk-heterojunction layer in nonfullerene organic solar cells allows to effectively ameliorate inferior electron transportation by filling traps and optimizing electron pathways, leading to a better balance of charge transport in device. This mechanism, however, provides an incomplete understanding of the stronger photogeneration, long-lived excitons and simultaneously increased short-circuit current density (J_SC) and open-circuit voltage (V_OC) that also benefit from the n-doping. Herein we investigate how molecular n-dopant impacts the optical characteristics, intermolecular packing behavior, charge carrier dynamics and photovoltaic performance in the nonfullerene-based blend. When incorporating a prototypical n-type dopant N-DMBI into a benchmark PM6:Y6 blend, the crystallization of PM6/Y6 is facilitated and the crystal coherence length is elongated, which is correlated with the optical absorbance enhancement. N-doping is unveiled to prolong exciton lifetime by retarding germinate recombination (GR) both at donor/acceptor (D/A) interfaces and within constituent domains by dilating interspace, reducing trap states and decreasing exciton binding energy. Despite slower interfacial charge transfer across the enlarged D/A interspace due to dopant intercalation, exciton dissociation remains highly effective due to the impeded interfacial GR. Consequently, the champion inverted cell at an optimal N-DMBI content delivers a decent efficiency of 15.34%, which is among the highest of the state-of-the art analogous PM6:Y6-based binary cells. Such improvement is largely ascribed to the concurrent increase of J_SC (up to 26.41 mA cm⁻²) and V_OC (up to 0.86 V) in comparison to the undoped device.

更新日期：2022-08-15

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