Data for paper "Electron affinity and binding energy of excitons in disordered organic semiconductors. II. First principles simulations and inverse photoemission studies for MADN"

Figure data of paper "Electron affinity and binding energy of excitons in disordered organic semiconductors. II. First principles simulations and inverse photoemission studies for MADN"Abstract: Key quantities for designing new opto-electronic devices that are based on disordered organic semiconductors, such as organic light-emitting diodes (OLEDs), are the frontier orbital energies, exciton energies and exciton binding energies. Obtaining these quantities spectroscopically with a high accuracy is complicated by the non-adiabaticity of such experiments. Here, we present for two isomers of the blue-emitting prototypical OLED material MADN (2-methyl-9,10-bis(naphthalen-2-yl)anthracene) multiscale first-principles simulations of optical absorption spectra and of the electron affinity, EA, a theoretical prediction and analysis of low-energy inverse photoemission spectroscopy (LEIPS) spectra that probe EA and experimental LEIPS spectra. The simulations combine many-body Green’s function theory, polarizable film-embedding, and multimode electron-vibrational coupling. We show how the onset energy of LEIPS spectra, which is commonly used to estimate EA, can differ from the actual adiabatic value, depending on material parameters and the instrumental resolution. For the two isomers of MADN, the theoretical and experimental onset energies differ by about 0.20–0.25 eV, which is within the expected uncertainty margin. However, the experimentalspectra are almost featureless, whereas the theoretical spectra show a clear peak structure. An extensive study is presented of the possible effects of thin film charging on the spectra, including charging of deep trap states. The calculated optical absorption spectra agree excellently with experiment, with a peak energy difference of only about 0.05 eV. For the two isomers of MADN, the calculated adiabatic singlet exciton binding energies are 1.0–1.1 eV.

论文《无序有机半导体中激子的电子亲和能与结合能。II. MADN的第一性原理模拟与逆光电发射研究》的配图数据
摘要：设计基于无序有机半导体的新型光电器件（如有机发光二极管（OLED））的关键参数包括前沿轨道能级、激子能量及激子结合能。由于此类实验存在非绝热性，通过光谱手段高精度获取这些参数颇具挑战。本文针对蓝色发光典型OLED材料MADN（2-甲基-9,10-二(2-萘基)蒽）的两种异构体，开展了光学吸收光谱与电子亲和能（electron affinity, EA）的多尺度第一性原理模拟，同时对探测电子亲和能的低能逆光电发射光谱（low-energy inverse photoemission spectroscopy, LEIPS）进行了理论预测与分析，并提供了实验LEIPS光谱数据。该模拟结合了多体格林函数理论、极化薄膜嵌入模型以及多模式电子-振动耦合。本文阐明了通常用于估算电子亲和能的LEIPS光谱起始能量如何与实际绝热值产生偏差，这一偏差取决于材料参数与仪器分辨率。针对MADN的两种异构体，理论与实验得到的起始能量差值约为0.20–0.25 eV，处于预期的不确定度范围内。然而，实验光谱几乎无特征结构，而理论光谱则展现出清晰的峰状结构。本文还系统研究了薄膜充电（包括深陷阱态充电）对光谱的潜在影响。计算得到的光学吸收光谱与实验结果吻合极佳，峰值能量差仅约0.05 eV。针对MADN的两种异构体，计算得到的绝热单重态激子结合能为1.0–1.1 eV。