Organic semiconductors have shown magnetic field responses in electrical currents. This phenomenon has been generally attributed to hyperfine interaction (HFI) and spin–orbit coupling (SOC). For the first time, we report the experimental and theoretical studies on hyperfine interaction vs. spin–orbit coupling in one thin film of organic semiconductor poly [9,9-di-n-hexyl-fluorenyl-2,7-diyl] and the dramatic influence of doping the PFO with complexes of bis [2-(2′-benzothienyl)-pyridinato-N, C3′] iridium (acetyl-acetonate). The intra-molecular HFI and SOC are only dependent on the intra-molecular interaction among electrons, nuclei and orbital field in a given molecule. Phosphorescence and fluorescence spectroscopies were used to measure the spin–orbit coupling strength. Furthermore, HFI is a short-range interaction and inter-molecular HFI is negligible. Inter-molecular SOC depends not only on molecular structure but also distance between adjacent molecules. Inter-molecular SOC strength increases strongly when the distance between adjacent molecules is decreased.

Understanding and modulating the spin-pair correlation of conjugated polymer materials in π-conjugated polymer light-emitting devices (PLEDs) plays a crucial role in the development of their applications. We investigated the relationships between the internal hyperfine interactions (HFIs), triplet–triplet annihilation (TTA), and triplet–charge annihilation (TCA) spin evolution processes in π-conjugated PLED. Research has shown that in a unipolar π-conjugated PLED, the “M” shaped ultra-small magnetic field effect is due to the HFI between hole polarons and the spin-mixing process of charge carriers. Under high magnetic fields (15 mT<|B|<350 mT), the TCA process dominates the negative magneto-conductance (MC), and its intensity and sign are not controlled by temperature. In polar π-conjugated PLED, excess carriers can provide conditions for the generation of TCA. Moreover, π-conjugated polymers (emission layers) have relatively strong electron–phonon coupling, which can capture triplet excitons into adjacent organic layers to obtain higher triplet exciton concentrations, resulting in the TTA process. Under low-temperature conditions, excess carriers induce the magneto-electroluminescence (MEL) effect to undergo TTA and form P-type delayed fluorescence. This study can provide a new mechanism explanation for the HFI in PLED devices and a new approach for the effective utilization of triplets.

Although the effect of the conductive polymers PEDOT:PSS on the electroluminescence performance of doped-type organic light-emitting diodes (OLEDs) has been studied, the process of PEDOT:PSS regulation of exciton recombination region and concentration within the deoxyribonucleic acid (DNA)-based doped-type BioLEDs is still obscure. In this study, we fabricated Bio-devices with and without PEDOT:PSS using varying spin-coating speeds of PEDOT:PSS. The Alq₃:Rubrene-based BioLEDs achieve higher luminance (44,010 cd/m²) and higher luminance efficiency (8.1 cd/A), which are increased by 186% and 478%, respectively, compared to the reference BioLEDs without PEDOT:PSS. Similarly, the maximum luminance and efficiency of blue TCTA:TPBi exciplex-type BioLEDs are increased by 224% and 464%. In particular, our findings reveal that with an increasing thickness of PEDOT:PSS, the region of exciton recombination shifts towards the interface between the emitting layer (EML) and the hole transport layer (HTL). Meanwhile, the concentration of singlet exciton (S_1,Rub) and triplet exciton (T_1,Rub) increases, and the triplet-triplet annihilation (TTA) process is enhanced, resulting in the enhanced luminescence and efficiency of the devices. Accordingly, we provide a possible idea for achieving high performance doped-type BioLEDs by adding conductive polymers PEDOT:PSS, and revealing the effect of exciton recombination and conversion in BioLEDs given different PEDOT:PSS thicknesses.

对于RGB有机电致发光器件(OLEDs), 蓝光非常重要. 在现有各种蓝光材料中, 聚芴（PFO）非常稳定且荧光量子效率可达80%，但它有一个非常大的缺点：电致发光会产生异常绿光带. 这严重影响了PFO相关器件的饱和色纯度. 本文使用分子基磁性材料Fe(NH2trz)3.(BF4)2掺杂PFO方法，解决了这一难题. 以ITO为衬底，制作了结构为ITO/PEDOT:PSS/PFO: Fe(NH2trz)3.(BF4)2/ CsCl/Al的器件. 报道了利用Fe(NH2trz)3.(BF4)2特殊的电子自旋态调制PFO的光电特性，实现了PFO的强烈纯正蓝光发射. 详细研究了Fe(NH2trz)3.(BF4)2对PFO光电特性的影响. 在电压4 V至9 V的偏置下，没有Fe(NH2trz)3.(BF4)2的器件, 发出特别异常的绿光. 然而, 与此形成明显对照的是：Fe(NH2trz)3.(BF4)2掺杂的器件发出强烈的本征蓝光；PFO绿色发光带被成功压制；随着电压的变化，器件光谱的蓝光部分在整个EL谱所占比例没有改变. 运用光电磁一体化测量技术，进一步研究了PFO掺杂Fe(NH2trz)3.(BF4)2器件的磁发光（MEL）和磁电导（MC）效应. 发现PFO：Fe(NH2trz)3.(BF4)2和纯PFO薄膜内都没有激基缔合物产生. 运用发光动力学理论，分析了Fe(NH2trz)3.(BF4)2阻断PFO异常绿光发射的机理.