Double Electron Transport Layers Research Articles

The 3 D Structure of Twisted Benzo[ghi]perylene-Triimide Dimer as a Non-Fullerene Acceptor for Inverted Perovskite Solar Cells.

Here, we introduced benzo[ghi]perylenetriimide (BPTI) derivatives including monomer and twisted dimer (t-BPTI) as an alternative electron-transport layer (ETL) material to replace the commonly used PC61 BM in inverted planar heterojunction perovskite solar cells (PSCs). Moreover, the double ETL was applied in our PSCs with structure of glass/ITO/PEDOT:PSS/perovskite/BPTI/C60 or PDI-C4/BCP/Al. The use of a double ETL structure can effectively eliminate the leakage current. The devices with the t-BPTI/C60 double ETL yield an average power conversion efficiency of 10.73 % and a maximum efficiency of 11.63 %. The device based on the complete non-fullerene electron acceptors of t-BPTI/PDI-C4 as double ETL achieved maximum efficiency of 10.0 %. Moreover, it was found that the utilization of alloy t-BPTI+BPTI as ETL can effectively reduce the hysteresis effect of PSCs. The results suggest that BPTI-based electron-transport materials are potential alternatives for widely used fullerene acceptors in PSCs.

White-light-emitting organic electroluminescent devices with poly-TPD as emitting layer

We report a method to achieve white organic light-emitting diodes (WOLEDs) with poly {N,N′-bis (4-butylphenyl)-N,N′-bis(phenyl)-benzidine} (poly-TPD) as single emitting layer. Monomer emission, excimer and electromer emission are all observed from poly-TPD, and combining them the white light emission with color coordinate of Commission International de L’Eclairage (CIE) (0.37, 0.31) was achieved. Double electron transport layer with apposite thickness 1,3,5-tris(1-phenyl-1H-benzimida-zol-2-yl) benzene (TPBi) (30 nm) and tris(8-hydroxyquinolato) aluminum (Alq3) (20 nm) were introduced to improve the performance of WOLEDs. The brightness reached 1000 cd/m2 at 22 V with an efficiency of 1.0 cd/A.

Ternary organic solar cells based on ZnO-Ge double electron transport layer with enhanced power conversion efficiency

Abstract A ZnO-Ge bilayer was proposed as an electron transport layer (ETL) in inverted ternary organic solar cells (OSCs). The energy level alignment, surface morphology, optical and electrical properties, and interface charge transfer were investigated to understand the impact of the additional Ge NPs layer. The results indicated that apart from improving the energy level alignment, the Ge NPs layer optimizes the interfacial contact between the active layer and ETL. Moreover, the ZnO-Ge bilayer shows better optical transmittance and perpendicular electrical transport properties compared to that of ZnO NPs layer. Benefit from the enhanced charge transfer from the active layer to ETL, the champion power conversion efficiency (PCE) was significantly increased to 9.15% by introducing the additional Ge layer, which exhibited a 18.4% improvement compared to that of the ZnO-only devices. Our results demonstrated the feasibility of ZnO-Ge bilayer as the ETL for high-performance OSCs.

High efficiency perovskite solar cells using a PCBM/ZnO double electron transport layer and a short air-aging step

Solution processed CH3NH3PbIxCl3–x based planar heterojunction perovskite solar cells with power conversion efficiency (PCE) above 14% are reported. The devices benefit from a phenyl-C61-butyric acid methyl ester (PCBM)/ZnO double electron transport layer (ETL) as well as a short air-aging step. The role of the additional ZnO ETL is studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and secondary ions mass spectroscopy (SIMS). Apart from improving the energy level alignment, the ZnO layer blocks the reactions between the metal electrode and perovskite components, increasing the air stability of the device. A crucial step in our processing is a short air-aging step for the device, which significantly increases the device performance by reducing the recombination process. Since the ZnO nanoparticle layer requires no thermal annealing, the maximum temperature to fabricate the device can be kept below 100°C, making this structure compatible with roll-to-roll processing on plastic films.

双电子传输层对有机发光二极管效率及其衰减的改善

Efficiency and its roll-off are improved by using double electron transport layers( DETLs)in organic light-emitting diodes( OLEDs). When DETLs of Bphen/BCP are employed,device efficiency is enhanced by 10% compared to the device with single Bphen as an electron transport layer( ETL) because of lower hole leakage current. Meanwhile,due to more electrons injected,efficiency roll-off of 0% is observed for the Bphen/BCP-based device with the increase of current density from 50 to 600 m A/cm2. On the contrast,the device with single BCP as ETL has an efficiency rolloff of 16%,which is reduced from 2. 5 cd/A at 50 m A/cm2 to 2. 1 cd/A at 300 m A/cm2. Compared to the Cs2CO3∶ BCP-ETL-based device with an efficiency roll-off of 30% from 50 to 300 m A /cm2,device efficiency is declined by 0% within the range from 50 to 600 m A/cm2 as DETLs of Bphen/Cs2CO3∶ BCP are explored. The reason is the blocking of Cs atom interdiffusion into the emissive layer by the Bphen of Bphen/Cs2CO3∶ BCP.