Lee Dongchan, Kim Do Hui, Oh Chang-Mok, Park Sujung, Krishna Narra Vamsi, Wibowo Febrian Tri Adhi, Hwang In-Wook, Jang Sung-Yeon, Cho Shinuk
Department of Semiconductor Physics and EHSRC, University of Ulsan, Ulsan 44610, Republic of Korea.
Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.
Polymers (Basel). 2023 Oct 10;15(20):4042. doi: 10.3390/polym15204042.
In conventional fullerene-based organic photovoltaics (OPVs), in which the excited electrons from the donor are transferred to the acceptor, the electron charge transfer state () that electrons pass through has a great influence on the device's performance. In a bulk-heterojunction (BHJ) system based on a low bandgap non-fullerene acceptor (NFA), however, a hole charge transfer state () from the acceptor to the donor has a greater influence on the device's performance. The accurate determination of is essential for achieving further enhancement in the performance of non-fullerene organic solar cells. However, the discovery of a method to determine the exact remains an open challenge. Here, we suggest a simple method to determine the exact level via deconvolution of the EL spectrum of the BHJ blend (EL). To generalize, we have applied our EL deconvolution method to nine different BHJ systems consisting of the combination of three donor polymers (PM6, PBDTTPD-HT, PTB7-Th) and three NFAs (Y6, IDIC, IEICO-4F). Under the conditions that (i) absorption of the donor and acceptor are separated sufficiently, and (ii) the onset part of the external quantum efficiency (EQE) is formed solely by the contribution of the acceptor only, EL can be deconvoluted into the contribution of the singlet recombination of the acceptor and the radiative recombination via . Through the deconvolution of EL, we have clearly decided which part of the broad EL spectrum should be used to apply the Marcus theory. Accurate determination of is expected to be of great help in fine-tuning the energy level of donor polymers and NFAs by understanding the charge transfer mechanism clearly.
在传统的基于富勒烯的有机光伏器件（OPV）中，供体激发的电子转移到受体，电子所经过的电荷转移态（）对器件性能有很大影响。然而，在基于低带隙非富勒烯受体（NFA）的本体异质结（BHJ）体系中，从受体到供体的空穴电荷转移态（）对器件性能有更大影响。准确测定对于实现非富勒烯有机太阳能电池性能的进一步提升至关重要。然而，发现一种确定确切的方法仍然是一个悬而未决的挑战。在此，我们提出一种通过对BHJ共混物的电致发光光谱（EL）进行反卷积来确定确切能级的简单方法。为了推广，我们将EL反卷积方法应用于由三种供体聚合物（PM6、PBDTTPD-HT、PTB7-Th）和三种NFA（Y6、IDIC、IEICO-4F）组合而成的九个不同的BHJ体系。在（i）供体和受体的吸收充分分离，以及（ii）外部量子效率（EQE）的起始部分仅由受体的贡献单独形成的条件下，EL可以反卷积为受体的单线态复合贡献和通过的辐射复合贡献。通过对EL的反卷积，我们已经明确确定了宽EL光谱的哪一部分应被用于应用马库斯理论。通过清楚地理解电荷转移机制，准确测定有望在微调供体聚合物和NFA的能级方面有很大帮助。
