Oh Chang-Mok, Lee Jihoon, Park Sung Heum, Hwang In-Wook
Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.
Department of Physics, Pukyong National University, Busan 48513, Republic of Korea.
J Phys Chem Lett. 2021 Jul 15;12(27):6418-6424. doi: 10.1021/acs.jpclett.1c01496. Epub 2021 Jul 8.
Carrier generation dynamics in binary PTB7-Th:CO8DFIC (1:1.5) and ternary PTB7-Th:CO8DFIC:PCBM (1:1.05:0.45) composites were investigated to identify the origins of high power conversion efficiencies (PCEs) in ternary bulk-heterojunction (BHJ) organic solar cells. Steady-state photoluminescence and time-resolved photoinduced absorption spectroscopic analyses revealed that the ternary composite exhibited faster hole transfer from CO8DFIC to PTB7-Th (8 ps compared to 21 ps in the binary composite), which led to an improved exciton separation yield in CO8DFIC (94% compared to 68% in the binary composite). Improved intermixing of the component materials and efficient electron transfer from CO8DFIC to PCBM facilitated enhancement in the hole transfer rate. The CO8DFIC-to-PCBM electron transfer promoted an electron transport cascade over PTB7-Th, CO8DFIC, and PCBM, which efficiently deactivated back-electron transfer (carrier recombination loss) from CO8DFIC to PTB7-Th at ∼160 ps and assisted in improving the PCE of the ternary BHJ cell (13.4% compared to 10.5% in the binary BHJ cell).
研究了二元PTB7-Th:CO8DFIC（1:1.5）和三元PTB7-Th:CO8DFIC:PCBM（1:1.05:0.45）复合材料中的载流子产生动力学，以确定三元体异质结（BHJ）有机太阳能电池中高功率转换效率（PCE）的来源。稳态光致发光和时间分辨光致吸收光谱分析表明，三元复合材料表现出更快的空穴从CO8DFIC转移到PTB7-Th（8皮秒，而二元复合材料中为21皮秒），这导致CO8DFIC中的激子分离产率提高（94%，而二元复合材料中为68%）。组分材料更好的混合以及空穴从CO8DFIC到PCBM的有效电子转移促进了空穴转移速率的提高。从CO8DFIC到PCBM的电子转移促进了电子在PTB7-Th、CO8DFIC和PCBM上的传输级联，这在约160皮秒时有效地抑制了从CO8DFIC到PTB7-Th的背向电子转移（载流子复合损失），并有助于提高三元BHJ电池的PCE（13.4%，而二元BHJ电池中为10.5%）。
