Pyrene-stabilized acenes as intermolecular singlet fission candidates: importance of exciton wave-function convergence
Pyrene-stabilized acenes as intermolecular singlet fission candidates: importance of exciton wave-function convergence
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DOI：
10.1088/1361-648x/ab699e
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发表时间：
2020-05-01
影响因子：
2.7
通讯作者：
Marom, Noa
中科院分区：
文献类型：
--
作者：
Liu, Xingyu;Tom, Rithwik;Marom, Noa
单重态裂变（英语：Singlet fission，简称SF）是一种物理过程，被认为是一种可能的方案，通过从一个高能光子产生两个三重态激子来绕过肖克利-奎塞尔极限。多并苯晶体，如并四苯和并五苯，在理论和实验上都显示出优异的SF性能。然而，它们的不稳定性使它们不能用于SF基光伏器件。为了寻找实用的SF发色团，我们在GW近似下用多体微扰理论和Bethe-Salpeter方程研究了一类芘稳定的并苯的激子性质。我们提出了一个标准来定义的激子波函数的收敛相对于使用的BerkeleyGW代码中的精细k点网格。一个开源的Python代码，执行激子波函数收敛检查和简化的双Bader分析激子字符。我们发现芘稳定的并苯中的单重态激子比相应的并苯具有更高程度的电荷转移特性。芘稠合的并四苯和并五苯衍生物表现出与其相应的并苯相当的激发能，使它们成为潜在的SF候选者。芘稳定的蒽衍生物被认为是一个可能的候选三重态-三重态湮灭，因为它产生了较低的SF驱动力比蒽。
Singlet fission (SF) is a photophysical process considered as a possible scheme to bypass the Shockley-Queisser limit by generating two triplet-state excitons from one high-energy photon. Polyacene crystals, such as tetracene and pentacene, have shown outstanding SF performance both theoretically and experimentally. However, their instability prevents them from being utilized in SF-based photovoltaic devices. In search of practical SF chromophores, we use many-body perturbation theory within the GW approximation and Bethe-Salpeter equation to study the excitonic properties of a family of pyrene-stabilized acenes. We propose a criterion to define the convergence of exciton wave-functions with respect to the fine k-point grid used in the BerkeleyGW code. An open-source Python code is presented to perform exciton wavefunction convergence checks and streamline the double Bader analysis of exciton character. We find that the singlet excitons in pyrene-stabilized acenes have a higher degree of charge transfer character than in the corresponding acenes. The pyrene-fused tetracene and pentacene derivatives exhibit comparable excitation energies to their corresponding acenes, making them potential SF candidates. The pyrene-stabilized anthracene derivative is considered as a possible candidate for triplet-triplet annihilation because it yields a lower SF driving force than anthracene.