Recently, most of the record-breaking PSCs are used formamidinium lead triiodide (FAPbI3) as the perovskite absorber due to its narrow bandgap. To stabilize the α-phase of FAPbI3, one of the common ways is introducing MAPbBr3 (where MA is methylammonium) into the perovskite layer. However, the MA+ will sacrifice the thermal stability of devices, while the incorporation of Br– will enlarge the optical bandgap and eventually decreased the photocurrent of PSCs. Here, a convenient strategy is presented to sequentially deposit stable FAPbI3 perovskite layer without MA+/ Br– by introducing the two-dimensional (2D) perovskite materials PMACl. It is speculated that the PMACl can form a 2D structure in grain boundaries which plays the role of template for the growth of α-FAPbI3. In addition to tune the phase transition, the PMACl can improve the crystallization and smooth the morphology of perovskite. As a result, the PSCs with PMACl achieve a PCE of 16.19%, while the control device only exhibits a PCE of 10.67%. This novel method avoids introducing the MA+/ Br–, and provides a facile approach for the efficient FAPbI3 perovskite solar cells.
Achieving high power conversion efficiency (PCE) without compromising device stability is an essential trade-off for commercializing organic solar cells (OSCs). In this study, a novel organic-inorganic hybrid material of tin oxide (SnO2) nanoparticles (NPs) and perylene diimide derivative (PDINO) is introduced as the electron transport layer (ETL) to improve both the device performance and the device stability of non-fullerene OSCs. Compared with the pristine SnO2 NP ETL-based device, not only the PCE of the PM6:IT-4F OSC with SnO2:PDINO as ETL is efficiently improved from 11.3 % to 12.7 %, but the shelf life of the SnO2:PDINO ETL based device is also extended. After being stored in ambient condition without encapsulation for 360 h, the PCE of the modified ETL-based OSC still retains 80 % of its original value. The incorporation of PDINO dopant can provide more favorable interfacial properties between the ETL and the active layer as well as reduced surface defects of SnO2 NP ETL, thus contributing to charge transport efficiency, suppressing molecular recombination, and protecting the active layer from degradation.
Recently, organic metal halide perovskites have attracted wide attention in the field of photovoltaic devices due to series of excellent photoelectric properties. However, the device performance is limited by a large number of surface defects in the perovskite film. Finding an effective method for defect passivation of perovskite film is considered to be a preferred strategy to further improve the performance of perovskite photovoltaic devices. Here, we use an organic metal salt, sodium alginate (SA), to passivate the surface defects of perovskite films to prepare high-performance perovskite photodetectors (PePDs). We find that the introduction of SA can improve the quality of perovskite active layer and passivate the surface defects effectively, which reduce the carrier recombination probability to increase the photocurrent and reduce the dark current of the PePDs. And the detectivity (D*) at 600 nm reaches 3.6×1012 Jones, three times that of the controlled devices. Meanwhile, the PePDs doped with sodium alginate have better stability and device life, which remains 82% of the original performance after being placed in the atmosphere for 7 days. These results indicate that it is an effective strategy to passivate perovskite film with organic metal salt to prepare high-performance PePDs.
Laser projectors are more and more widely used because of their large screen, and high brightness. However, the stray light outside the screen affects the user's viewing effect dramatically. In some cases, it looks like there's a halo on the top, or loos like some light outside the picture in the black. Since the stray light comes from the reflection of mechanical structural parts in the lens, and some stray light is launched by the light on digital micromirror device (DMD) off state in the illumination system, how to carry out theoretical analysis effectively is a difficult problem. On the other hand, how to trace stray light back to the source after it hits the screen and reduce it is also a challenge. Herein, some effective theoretic analysis methods and practical analysis methods are put forward, and effective countermeasures are given. Through experiments, the stray light situation is effectively improved.
Recently, ternary semi-transparent organic photovoltaics (STOPVs) have developed rapidly due to their impressive application prospect in vegetable greenhouse, smart light window, and building-integrated solar cells. However, STOPVs have special requirements for the thickness of the active layer, which will affect the performance of the solar cells. Therefore, a new method developed to trade off device performance and average transmittance (AVT) are extremely important. Herein, we used an insulating polymer poly(N-vinylcarbazole) (PVK) as a color control agent to improve the AVT without changing the power conversion efficiency (PCE) of ternary STOPVs. Through mixing of PVK, the STOPVs show remarkable enhancement of the hole mobility and visible light transmittance, which leading the AVT of the device reaches 23.2% while maintaining the PCE over 14%. This method can effectively realize the preparation of high-performance neutral STOPVs, which is worthy of further promotion and research.
KEYWORDS: Polymers, Polymerization, Interfaces, Zinc oxide, Solar cells, Organic photovoltaics, Polymer thin films, Electrodes, Control systems, Solar energy
Electro-chemical polymerization has identified to be a facile and useful method for the preparation of electroactive and conducting polymer films, and capability of precise control of the film properties. With this strategy, a large number of conjugated polymers were developed as specific interface modification layers to meet the requirements from various electronic equipment. Here we report the synthesis of conjugated polymer film prepared by in situ electro-chemical polymerization as effective interface modification layer between ITO and ZnO in organic solar cells. By optimizing the polymerization potential to control accurately the thickness of conjugated polymer layer, the resulting devices show significantly enhancement of short-circuit current, with an optimized power conversion efficiency (PCE) of 14.9%. As a result, the reasonable interface modification strategy via electro-chemical polymerization seems to be able to bring a new design perspective for the development of high-performance organic solar cells.
Organic-inorganic hybrid perovskites have been emerging as promising emitting materials for light-emitting diodes due to their miraculous optoelectronic properties. Conventional electron transporting materials used in organic light emitting diodes (OLEDs) such as 1,3,5-tris(2-N-phenylbenzimidazolyl) benzene (TPBi), 4,7-diphenyl-1,10-phenanthroline (Bphen), 1,3,5-tri(m-pyrid-3-yl-phenyl) benzene (TmPyPB), and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) have been used as electron transporting layer (ETL) in the perovskite light emitting diodes (PeLEDs). However, there exit few systematic analysis about different ETL materials on the performance of PeLED. In this work, we employ TPBi, BPhen, TmPyPB, and BCP as ETL material of PeLED, respectively. Owing to the high electron mobility and suitable energy level, BPhen PeLED express the best performance at the same thickness with a maximum luminance of 812 cd m2 and current efficiency (CE) of 0.1 cd A-1. Hence, this work provides a useful method on device architecture construction for the realization of high performance PeLEDs.
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