Organic Electronics最新文献

{"title":"Novel isocyanobenzene carbazole-based thermally activated delayed fluorophors towards solution-processed blue emitting OLED devices with high efficiency","authors":"Yang Xiao ,&nbsp;Tianyu Huang ,&nbsp;Guimin Zhao ,&nbsp;Wei Jiang ,&nbsp;Dongdong Zhang ,&nbsp;Lian Duan","doi":"10.1016/j.orgel.2024.107155","DOIUrl":"10.1016/j.orgel.2024.107155","url":null,"abstract":"<div><div>Achieving efficient blue emission is an exigent challenge for the application of thermally activated delayed fluorescent organic light-emitting diodes (TADF-OLEDs). Carbazole benzonitrile-based TADF molecules exhibit promising performance in achieving the goal. Here, by replacing the cyano group in the sensitizer with the isocyano group, a 9 nm hypochromatic shift in photoluminescence spectra of the sensitizer and an enhanced efficiency of the Förster energy transfer (FET) in TADF-sensitized fluorescence (TSF) is found. By using the isocyano-based compounds as sensitizers, a maximum external quantum efficiency of 24.5 % is obtained in solution-processed OLEDs, surpassing the cyano-based counterparts with similar structures. Moreover, the full width at half maximum (FWHM) of the emitter in the electroluminescence spectrum is also decreased from 47 nm to 38 nm, indicating a more complete energy transfer.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"137 ","pages":"Article 107155"},"PeriodicalIF":2.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multifunctional thermally activated delayed fluorescence emitter for both doped and non-doped organic light emitting diodes","authors":"Nisha Yadav,&nbsp;Pachaiyappan Rajamalli","doi":"10.1016/j.orgel.2024.107157","DOIUrl":"10.1016/j.orgel.2024.107157","url":null,"abstract":"<div><div>Developing efficient smart materials that display mechanochromic luminescence (MCL) and thermally activated delayed fluorescence (TADF) remains a formidable challenge. Herein, we designed and synthesized a multifunctional emitter, 2BPy-<em>m</em>TC, where benzoyl pyridyl (2BPy) acts as an acceptor and 3,6-di-<em>tert</em>-butyl-9<em>H</em>-carbazole (TC) acts as a donor. 2BPy-<em>m</em>TC exhibits blue emission with <em>λ</em>_<em>max</em> of 456 nm in pristine form and emission shifted to green with <em>λ</em>_<em>max</em> of 495 nm upon grinding. Interestingly, when fumed with CH₂Cl₂, the emission reverts to deep blue at <em>λ</em>_<em>max</em> of 440 nm. 2BPy-<em>m</em>TC possesses a <em>ΔE</em>_<em>ST</em> of 0.20 eV in neat film and 0.11 eV in doped film (5 wt% 2BPy-<em>m</em>TC: <em>m</em>CBP) and exhibits a PLQY of 42 % in neat film and 59 % in doped film. The transient photoluminescence (PL) decay curves show a delayed lifetime of 110.3 μs for the neat film and 192.9 μs for the doped film and confirm the TADF property in both doped and non-doped film. It shows an <em>EQE</em>_<em>max</em> of 16.3 % in doped device with an emission maximum of 484 nm. Conversely, it retains the <em>EQE</em>_<em>max</em> of 13.8 % in non-doped device with a slight red shift in the emission maximum (496 nm). This discovery opens a new avenue for designing multifunctional emitters with improved EL performance.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107157"},"PeriodicalIF":2.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent progress in high-performance thermally activated delayed fluorescence exciplexes based on multiple reverse intersystem crossing channels","authors":"Huitian Du ,&nbsp;Yaming Hao ,&nbsp;Xijian Zhang ,&nbsp;Shuyuan Zhang ,&nbsp;Qiang Liu ,&nbsp;Zhiyong Pang","doi":"10.1016/j.orgel.2024.107159","DOIUrl":"10.1016/j.orgel.2024.107159","url":null,"abstract":"<div><div>In the field of organic light-emitting diodes (OLEDs), exciplex materials with thermally activated delayed fluorescence (TADF) characteristics have garnered significant attention in recent years owing to their potential for high fluorescence efficiency, primarily achieved through the reverse intersystem crossing (RISC) process. By converting non-radiative triplet states to radiative singlet states, the RISC process can effectively regulate exciton behavior, resulting in the harvest of triplet excitons and the improvement of luminescence efficiency. Recently, multi-RISC strategies have been developed to further enhance the performance of TADF exciplex materials and devices. In this paper, we review these research progress in this area. We classify molecular design strategies according to the composition of exciplexes, discuss the design principles and energy-harvesting mechanism of high-performance TADF exciplexes based on multi-RISC strategies, and prospect their further research and development. The progressive endeavors summarized in this review may inspire further research on material design and device fabrication, and promote the development of OLED applications.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107159"},"PeriodicalIF":2.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancing the emissive film quality: A new role of TADF materials for high-performance blue perovskite light-emitting diodes","authors":"Dengduan Zheng ,&nbsp;Yubu Zhou ,&nbsp;Yi Dai ,&nbsp;Lingjiao Zhang ,&nbsp;Qiuyu Long ,&nbsp;Baiquan Liu","doi":"10.1016/j.orgel.2024.107158","DOIUrl":"10.1016/j.orgel.2024.107158","url":null,"abstract":"<div><div>Thermally activated delayed fluorescence (TADF) materials are widely used in the field of organic light-emitting diodes (OLEDs) because they can capture both singlet and triplet excitons for light emission. However, only scare attention has been paid to the application of TADF materials in perovskite LEDs (PeLEDs) and the understanding of effects of TADF materials in PeLEDs is limited. In this study, a new role of TADF materials for achieving high-quality perovskite films to enhance the performance of PeLEDs is emphasized. TADF materials are introduced into quasi-2D blue PeLEDs to assist in the crystallization of perovskites during film annealing and ensure the formation of high-quality films with reduced defects, enhancing device performance. Additionally, a step-like hole transport layer has been constructed to reduce the hole transport barrier, which can further enhance the performance of PeLEDs. The resultant blue PeLEDs exhibits an external quantum efficiency of 5.44 %, which is 12.7-fold higher than that of the control device. Furthermore, a turn-on voltage of 2.6 V is achieved, which is the lowest for TADF-based blue PeLEDs. The findings may not only unlock a new role of TADF materials in blue PeLEDs, but also provide an alternative pathway to achieve high-performance PeLEDs.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107158"},"PeriodicalIF":2.7,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Theoretical exploration on the combined effect of isoelectron B-N bonds and B-N resonance skeleton on the thermally activated delayed fluorescence property","authors":"Lan Zhang ,&nbsp;Jing Gao ,&nbsp;Qi Wu ,&nbsp;Hua-Zheng Dong ,&nbsp;Ujala Khan ,&nbsp;Yun Geng ,&nbsp;Liang Zhao ,&nbsp;Zhong-Min Su ,&nbsp;Min Zhang ,&nbsp;Ying Gao","doi":"10.1016/j.orgel.2024.107154","DOIUrl":"10.1016/j.orgel.2024.107154","url":null,"abstract":"<div><div>The multiple resonance thermally activated delayed fluorescence (MR-TADF) materials has become a hot spot in recent years depending on their potential in achieving an internal quantum efficiency of 100 %. The combined effect of para B-N resonance skeleton and isoelectron B-N bonds on the TADF property was investigated in details by employing density functional theory/time-dependent density functional theory (DFT/TDDFT) in this work based on four polycyclic aromatic molecules. The results show that isoelectron B-N bonds are favorable to the enhancement of spin orbital coupling (SOC) constants between the first singlet state (S₁) and the first triplet state (T₁), while para B-N resonance skeleton is more conducive to reducing the energy gap between S₁ and T₁ (Δ<em>E</em>_ST) through realizing short-range charge transfer character and keeping electron and hole localized at different atoms. Accordingly the combination of isoelectron B-N bonds and para B-N resonance skeleton in <strong>m[B-N]N1</strong> and <strong>m[B-N]N2</strong> could realize faster intersystem crossing (ISC) and reverse intersystem crossing (RISC) processes through larger SOC and lower Δ<em>E</em>_ST compared with <strong>BCz-BN</strong> and <strong>NBN-2</strong> which only contain para B-N resonance skeleton and isoelectron B-N bonds, respectively. At the same time, the para B-N resonance skeleton help to stabilize the structure of polycyclic aromatic hydrocarbons and localize the vibration in low frequency region during emission from S₁ to ground state. Thus larger nonradiative rates induced by the rotation of carbazole and tert-butyl carbazole in low frequency region in <strong>m[B-N]N1</strong> and <strong>m[B-N]N2</strong> could be easily reduced by replacing them by small functional group such as electron-donating (-CH₃) and electron-withdrawing (-CN) groups. Therefore, we can obtain high TADF efficiency through combining para B-N resonance skeleton and isoelectron B-N bonds and suppressing low-frequency vibrations as in our designed molecules <strong>m[B-N]CH</strong>_{<strong>3</strong>} and <strong>m[B-N]CN</strong>.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107154"},"PeriodicalIF":2.7,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular engineering of oxadiazole-based small organic-functional molecules as hole transporting materials for dopant-free perovskite solar cells","authors":"Kishore Manda ,&nbsp;Vinod D. Jadhav ,&nbsp;Prabhakar Chetti ,&nbsp;Rambabu Gundla ,&nbsp;Someshwar Pola","doi":"10.1016/j.orgel.2024.107153","DOIUrl":"10.1016/j.orgel.2024.107153","url":null,"abstract":"<div><div>The present investigation concerns the synthesis and characterization of new hole-transporting materials (HTMs) for dopant free perovskite solar cells (PSCs). In this work, emphasis is placed on three new HTMs, specifically materials P-H, P-OMe, and P-CN, whose center-core is 2,2'-(4,8-bis(octyloxy)benzo[1,2-b:4,5-b']dithiophene (OBDT) and combined with two donor units of substituted triphenylamine as at both ends along with oxadiazole acceptor units in between donor and OBDT. The fabrication of perovskite solar cell devices using new HTMs and compared the power conversion performance with the standard spiro-OMeTAD HTM. Several spectroscopic techniques were utilized to characterize the properties of the new HTMs, such as FESEM analysis of thin-film morphologies, time-dependent photoluminescence (PL) spectra, and mobility measurements. The HTMs P-OMe established a compressed and steady protective layer on the perovskite layer. This layer contributed to the development of open-circuit voltage (V_OC) and short-circuit current density (J_SC), both of which are crucial for accomplishing high power conversion efficiency (PCE) in PSCs. The PSC device integrating the P-OMe HTM displayed a superior PCE of 21.14 % over an active area of 0.22 cm². This activity was related to the standard device that utilized the standard Spiro-OMeTAD HTM, which accomplished a PCE of 17.46 %. The improved devices with the P-OMe HTM continued about 90 % of their initial PCE throughout maximum power point tracking (MPPT) for 90 days. Furthermore, these devices engaged in their activity over a further 2160 h under various temperature settings (25 °C and 35 °C), probably because of the hydrophobic property of the HTM.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107153"},"PeriodicalIF":2.7,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Novel integrated reference-counter electrode for electrochemical measurements of HOMO and LUMO levels in small-molecule thin-film semiconductors for OLEDs","authors":"Sevki C. Cevher,&nbsp;Kurt P. Pernstich","doi":"10.1016/j.orgel.2024.107152","DOIUrl":"10.1016/j.orgel.2024.107152","url":null,"abstract":"<div><div>Organic light-emitting diodes (OLEDs) are a prominent display technology, yet the accurate characterization of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels in their constituent materials remains challenging. This study introduces a novel integrated reference-counter electrode (IRCE) assembly, leveraging a gel polymer electrolyte with an embedded silver quasi-reference electrode, facilitating the electrochemical measurement of HOMO and LUMO levels in small molecular thin-film semiconductors. Calibration of the IRCE against ferrocene enables the establishment of an absolute energy scale. Comparative stability tests against a standard Ag/AgNO₃ reference electrode confirm the IRCE's reliability. Electrochemical characterization using cyclic voltammetry was performed on prototypical OLED materials, including NPB, TCTA, PO-T2T neat films, and an NPB:PO-T2T exciplex film. While NPB and PO-T2T exhibited stable voltammograms, TCTA showed signs of electropolymerization. Additionally, the HOMO level of the NPB:PO-T2T exciplex was slightly shifted compared to that of NPB, suggesting interactions within the exciplex. The results demonstrated the IRCE's capability to accurately determine frontier energy levels in thin films, paving the way for better device modeling and a better understanding of underlying electronic processes in organic semiconductors.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107152"},"PeriodicalIF":2.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spin effect in the ferromagnetic organic photovoltaics cells","authors":"Bin Tong ,&nbsp;Yuee Xie ,&nbsp;Yuanping Chen ,&nbsp;Zhongxuan Wang","doi":"10.1016/j.orgel.2024.107151","DOIUrl":"10.1016/j.orgel.2024.107151","url":null,"abstract":"<div><div>In organic photovoltaic devices, the separation and transport of photogenerated charges play crucial roles for power conversion efficiency. Magnetic doping in organic solar cells can effectively enhance the power conversion efficiency by introducing a static magnetic field. In this study, we observed that in pure organic magnetic solar cells, the spin-polarization-induced spin scattering effect can also efficiently modulate the photocurrent in solar cells. Compared to the demagnetized state, the short-circuit current of PTB7:nw-P3HT:PCBM solar cells increased by approximately 0.3 % after magnetization. The dielectric constant only increased by about 0.05 %. However, above the Curie temperature 310 K, the long-range spin order in PTB7:nw-P3HT:PCBM solar cells disappears, resulting in consistent circuit currents before and after magnetization. Therefore, magnetic doping can enhance the short-circuit current in organic solar cells by weakening the spin scattering effect and enhancing the charge carrier mobility.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107151"},"PeriodicalIF":2.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Blue-emission crystalline OLED doped with DMAC-DPS TADF material","authors":"Wantao Zheng ,&nbsp;Feng Zhu ,&nbsp;Donghang Yan","doi":"10.1016/j.orgel.2024.107150","DOIUrl":"10.1016/j.orgel.2024.107150","url":null,"abstract":"<div><div>Doping thermally activated delayed fluorescence (TADF) materials with high exciton utilization into crystalline hosts with high carrier mobility is an effective approach for developing novel OLEDs. This approach harnesses the strengths of both materials to realize high-performance blue light-emitting crystalline organic light-emitting diodes (C-OLEDs). Nevertheless, the high triplet energy levels of blue emitting TADF materials may facilitate the outflow of triplet excitons through Dexter energy transfer to the lower energy levels within the crystalline host, thus leading to efficiency losses in the device. In this study, we present a pioneering strategy designed to improve the exciton utilization efficiency of TADF materials in C-OLED by leveraging the up-conversion capability of TTA materials to reclaim triplet excitons. With a well-designed energy level structure, this device achieves a maximum EQE of 5.6 % and a low turn-on voltage of 2.7 V. The benefits of the crystalline host allowed for fast turn-on, and a rapid increase in brightness and current density, leading to significantly improved blue photon output and a lower series resistance Joule heat loss ratio. This work introduces a novel approach to employ TADF materials in crystalline hosts and manage excitons within the emissive layer of devices, aiming to develop high-performance C-OLEDs.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"135 ","pages":"Article 107150"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A strategy for achieving high-performance single layer polymer photodetectors through dark current reduction using PMMA additives","authors":"Guozhen Bai ,&nbsp;Luwen Ran ,&nbsp;Xinmu Chen,&nbsp;Zilong Wang,&nbsp;Zhidong Lou,&nbsp;Yanbing Hou,&nbsp;Feng Teng,&nbsp;Yufeng Hu","doi":"10.1016/j.orgel.2024.107149","DOIUrl":"10.1016/j.orgel.2024.107149","url":null,"abstract":"<div><div>Suppressing dark current density is crucial for optimizing the performance of organic photodetectors (PDs), particularly in terms of detectivity (D∗) and linear dynamic range (LDR). Organic PDs often utilize the bulk heterojunction structure of organic solar cells to significantly increase photocurrent. However, unlike solar cells, which are unaffected by dark current, photodetectors' performance is substantially limited by it. The interconnected network of bulk heterojunctions leads to a noticeable increase in dark current, thus degrading device performance. Typically, reducing dark current involves adding a modification layer or using multilayer planar heterojunctions, which effectively reduce dark current but often delay response speed and complicate manufacturing. This study presents an alternative approach by incorporating a small concentration of PMMA into single-layer polymer photodetectors, significantly reducing dark current without affecting photocurrent. For this single-layer polymer PD, an ultra-low dark current density of 1.25 × 10⁻⁸ A/cm², a high D_sh∗ of 2.74 × 10¹² Jones, an LDR of 120.5 dB, and a fast response time with 1.6 μs were achieved. The capacitance-voltage (C-V), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements revealed that the PMMA additive reduces internal defects, increases bulk resistance, optimizes phase separation, and enhances carrier transport efficiency. The improved device performances are attributed to a more efficient vertical arrangement of the donor-acceptor interface and carrier channels, thus reducing carrier recombination loss. These findings offer a new direction for fabricating high-performance single-layer photodetectors.</div></div>","PeriodicalId":399,"journal":{"name":"Organic Electronics","volume":"136 ","pages":"Article 107149"},"PeriodicalIF":2.7,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}