Fullerene acceptors typically possess excellent electron-transporting properties and can work as guest components in ternary organic solar cells to enhance the charge extraction and efficiencies. However, conventional fullerene small molecules typically suffer from undesirable segregation and dimerization, thus limiting their applications in organic solar cells. Herein we report the use of a poly(fullerene-alt-xylene) acceptor (PFBO-C12) as guest component enables a significant efficiency increase from 16.9% for binary cells to 18.0% for ternary all-polymer solar cells. Ultrafast optic and optoelectronic studies unveil that PFBO-C12 can facilitate hole transfer and suppress charge recombination. Morphological investigations show that the ternary blends maintain a favorable morphology with high crystallinity and smaller domain size. Meanwhile, the introduction of PFBO-C12 reduces voltage loss and enables all-polymer solar cells with excellent light stability and mechanical durability in flexible devices. This work demonstrates that introducing polyfullerenes as guest components is an effective approach to achieving highly efficient ternary all-polymer solar cells with good stability and mechanical robustness.
Graphics processing units (GPUs) have been accepted as a powerful and viable coprocessor solution in highperformance computing domain. In order to maximize the benefit of GPUs for a multicore platform, a mechanism is needed for CPU threads in a parallel application to share this computing resource for efficient execution. NVIDIA's Fermi architecture pioneers the feature of concurrent kernel execution; however, only kernels of the same thread context can execute in parallel. In order to get the best use of a GPU device in a multi-threaded application environment, this paper explores the techniques to effectively share a context, i.e., context funneling, which could be done either manually at application level, or automatically at the GPU runtime starting from CUDA v4.0. For synthetic microbenchmark tests, we find that both funneling mechanisms are more capable of exploring the benefit of concurrent kernel execution than traditional context switching, therefore improving the overall application performance. We also find that the manual funneling mechanism provides the highest performance and more explicit control, while CUDA v4.0 provides better productivity with good performance. Finally, we assess the impact of such techniques on a compact application benchmark, SSCA#3 -SAR sensor processing.
Electron transporting materials (ETMs) play vital roles in determining the efficiency and stability of inverted perovskite solar cells. The widely used PCBM is prone to undesirable aggregation and migration in a cell, thus impairing device stability. In this work, we develop a new type of ETMs by polymerizing C60 fullerene with an aromantic linker unit. The resultant polyfullerene (PFBS-C12) not only maintains the good optoelectronic properties of fullerenes, but also can address the aforementioned aggregation problem of PCBM. The polyfullerene-based blade-coated cells exhibit a high efficiency of 23.2 % and good device stability that maintain 96 % of initial efficiency after > 1300-hour light soaking. An aperture efficiency of 18.9 % is also achieved on a 53.6-cm 2 perovskite mini-module. This work provides a new strategy for designing ETMs that retain the key figure-of-merits of conventional fullerene molecules and enable more stable perovskite solar devices simultaneously.
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