Device Characteristics of CZTSSe Thin-Film Solar Cells with 12.6% Efficiency
Device Characteristics of CZTSSe Thin-Film Solar Cells with 12.6% Efficiency
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DOI：
10.1002/aenm.201301465
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发表时间：
2014-05-01
影响因子：
27.8
通讯作者：
Mitzi, David B.
中科院分区：
文献类型：
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作者：
Wang, Wei;Winkler, Mark T.;Mitzi, David B.
薄膜光伏材料Cu 2 ZnSnSxSe 4-x（CZTSSe）由于其优异的性能和地球资源丰富的成分而受到了广泛的关注。直到最近，[1]最先进的CZTSSe薄膜太阳能电池被限制在11.1%的功率转换效率（PCE），这些性能水平是通过肼浆料方法实现的。[2]其他基于真空和非真空的沉积技术也成功地制造了PCE高于8%的CZTSSe太阳能电池。[3，4]然而，即使记录设备的PCE为11%，仍然远远低于物理极限，称为Shockley-Queisser（SQ）极限，在陆地条件下约为31%的效率。[5]对于带隙为1.13 eV的太阳能电池，例如之前的11.1%冠军，[2]开路电压（Voc）和短路电流密度（Jsc）的SQ限值分别为820 mV和43.4 mA cm− 2。之前的11.1%冠军仅获得了460 mV的Voc和34.5 mA cm− 2的Jsc，分别相当于SQ限值的56%和79%。为了提高Jsc，最近报道了具有优化的透明导电氧化物（TCO）和CdS厚度的光学架构，导致新的CZTSSe记录PCE为12.0%，Jsc达到SQ限制的83%。[1]尽管短路电流有所改善，但等于带隙和Voc之差的Voc赤字目前是阻止CZTSSe器件实现更高效率的最大障碍。[6]Voc的增强还直接改善了器件填充因子。[7]虽然许多因素可以影响太阳能电池中的Voc，但电荷分离结附近的载流子产生和复合起主导作用。因此，为了减少Voc赤字并将效率提高到12%以上，理解当前一代器件中的结特性、电流收集和复合机制至关重要。在这里，一个独立认证的世界纪录12.6%PCE CZTSSe薄膜太阳能电池。新的冠军设备是使用最近描述的肼纯溶液方法制造的，目标是贫铜和富锌条件。[8]二次离子质谱（西姆斯）表明，所获得的CZTSSe薄膜表现出非常低的碳和氧浓度，可与由更高浓度的CZTSSe制备的薄膜相比。
The thin-film photovoltaic material Cu 2ZnSnS xSe 4–x (CZTSSe) has drawn world-wide attention due to its outstanding performance and earth-abundant composition. Until recently,[1] stateof-the-art CZTSSe thin-film solar cells were limited to 11.1% power conversion efficiency (PCE), with these performance levels being achieved via a hydrazine slurry approach.[2] Other vacuum-and non-vacuum-based deposition techniques have also been successful in fabricating CZTSSe solar cells with PCE above 8%.[3, 4] However, even record devices with PCE of 11% are still far below the physical limit, known as the Shockley-Queisser (SQ) limit, of about 31% efficiency under terrestrial conditions.[5]For a solar cell with 1.13 eV bandgap such as the previous 11.1% champion,[2] the SQ limits for open circuit voltage (Voc) and short-circuit current density (Jsc) are 820 mV and 43.4 mA cm− 2, respectively. The previous 11.1% champion only achieved a Voc of 460 mV and a Jsc of 34.5 mA cm− 2, corresponding to about 56% and 79% of the SQ limit values. In order to boost Jsc, an optical architecture with optimized transparent conductive oxide (TCO) and CdS thicknesses has recently been reported, leading to a new CZTSSe record PCE of 12.0% and a Jsc that reaches 83% of the SQ limit.[1] Despite improvements in shortcircuit current, the Voc deficit, equal to the difference between the bandgap and Voc, is currently the biggest hurdle preventing CZTSSe devices from achieving higher efficiency.[6] Enhancement of Voc also directly improves device fill factor.[7] Although many factors can influence Voc in a solar cell, carrier generation and recombination near the charge-separating junction play a dominant role. Thus, in order to decrease the Voc deficit and increase efficiency beyond 12%, it is critical to understand junction characteristics, current collection, and recombination mechanisms in the current generation of devices. Here, an independently certified world-record 12.6% PCE CZTSSe thin-film solar cell is presented. The new champion device was fabricated using a recently described hydrazine pure-solution approach, targeting a Cu-poor and Zn-rich condition.[8] Secondary ion mass spectrometry (SIMS) shows that the obtained CZTSSe films exhibit very low carbon and oxygen concentrations, comparable to films fabricated by the more