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arXiv 1801.01675cond-mat.mes-hallphysics.optics
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范德瓦尔斯层状材料中的高效载流子倍增

Highly Efficient Carrier Multiplication in van der Waals layered Materials

Ji-Hee Kim, Matthew R. Bergren, Jin Cheol Park, Subash Adhikari, Michael Lorke, Thomas Fraunheim, Duk-Hyun Choe, Beom Kim, Hyunyong Choi, Tom Gregorkiewicz, Young Hee Lee

摘要:

载流子倍增(CM)是通过利用自由载流子的过剩能量来产生多个电子-空穴对的光物理过程,其被探索用于来自蓝色太阳能带的光子的高效光伏转换,所述光子主要在标准太阳能电池中作为热量浪费。目前最先进的方法与纳米材料已经证明了改进的CM,但不令人满意的,由于高能量损失和固有的困难与载体提取。在这里,我们报告了范德瓦尔斯(vdW)层状材料中的超高效CM,其从节能极限开始,并以接近100%的转换效率进行。一个小的阈值能量,低至两倍的带隙,实现了,标志着量子产率与增强的载流子生成的开始。vdW层内的电子之间的强库仑相互作用允许快速的电子-电子散射胜过电子-声子散射。此外,在动量空间上散布的电子袋的存在也可以有助于高CM效率。结合高电导率和最佳带隙,这些优异的CM特性确定了第三代太阳能电池的vdW材料。

英文摘要:

Carrier multiplication (CM), a photo-physical process to generate multiple electron-hole pairs by exploiting excess energy of free carriers, is explored for efficient photovoltaic conversion of photons from the blue solar band, predominantly wasted as heat in standard solar cells. Current state-of-the-art approaches with nanomaterials have demonstrated improved CM but are not satisfactory due to high energy loss and inherent difficulties with carrier extraction. Here, we report ultra-efficient CM in van der Waals (vdW) layered materials that commences at the energy conservation limit and proceeds with nearly 100% conversion efficiency. A small threshold energy, as low as twice the bandgap, was achieved, marking an onset of quantum yield with enhanced carrier generation. Strong Coulomb interactions between electrons confined within vdW layers allow rapid electron-electron scattering to prevail over electron-phonon scattering. Additionally, the presence of electron pockets spread over momentum space could also contribute to the high CM efficiency. Combining with high conductivity and optimal bandgap, these superior CM characteristics identify vdW materials for third-generation solar cell.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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