Solar cells based on n+-AZO/p-BaSi2 heterojunction: Advanced opto-electrical modelling and experimental demonstration
Solar cells based on n+-AZO/p-BaSi2 heterojunction: Advanced opto-electrical modelling and experimental demonstration
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DOI：
10.1016/j.solmat.2021.111181
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发表时间：
2021-09
影响因子：
6.9
通讯作者：
Y. Yamashita;C. R. Tobon;R. Santbergen;M. Zeman;O. Isabella;T. Suemasu
中科院分区：
文献类型：
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作者：
Y. Yamashita;C. R. Tobon;R. Santbergen;M. Zeman;O. Isabella;T. Suemasu
我们对薄膜basi2太阳能电池进行了先进的光电模拟。首先，基于平面和/或金字塔纹理表面计算了硅衬底上basi2 -非均质结太阳能电池的吸收光谱，其中20 nm厚的+- basi2是最顶层的电子传输层。通过将前表面结构由平坦变为纹理，在波长（λ） 700 ~ 1200 nm范围内的反射率降低，500 nm厚- basi2层中光生载流子传递的光电流密度（Jph）增加了1.2 mA/cm2。模拟结果表明，抑制p- basi2层光吸收的关键因素是+- basi2和c-Si衬底中的寄生吸收。为了解决这些光学问题，我们提出了一种新的器件结构，Al-dopedn+-ZnO (AZO, 50 nm)/i-ZnO (20 nm)/p-BaSi2（500 nm）异质结太阳能电池（HJSC）。在这种器件结构中，寄生吸收大幅降低，jph达30.23 mA/cm2。此外，用玻璃衬底取代硅衬底后，捕光效果更好，jphto饱和所需的吸收层厚度降至1 μm，收率为32.06 mA/cm2。基于这些仿真结果，我们制作了dn+-AZO/p-BaSi2HJSC。在λ= 600 nm处，内部量子效率超过30%，这意味着我们首次证明了n+-AZO/p-BaSi2HJSC的运行。我们研究了与模拟结果相比效率低的原因，发现对p- basi2层缺陷进行钝化和减少其- zno /p- basi2界面的载流子复合将显著提高太阳能电池的性能。
We performed advanced opto-electrical simulations on thin-film BaSi2solar cells. First, absorption spectra of BaSi2-pnhomojunction solar cells on Si substrate were calculated based on flat and/or pyramidally-textured surfaces, wherein 20-nm-thickn+-BaSi2was the topmost electron transport layer. By changing the front surface structure from flat to texture, the reflectance decreased in the wavelength (λ) range 700–1200 nm and the photocurrent density (Jph) delivered by the photogenerated carriers in the 500-nm thickp-BaSi2layer increased by 1.2 mA/cm2. Simulations revealed that the key factor inhibiting light absorption in thep-BaSi2layer was parasitic absorption in then+-BaSi2and in the c-Si substrate. To solve these optical issues, we propose a new device structure, Al-dopedn+-ZnO (AZO, 50 nm)/i-ZnO (20 nm)/p-BaSi2(500 nm) heterojunction solar cell (HJSC). In this device structure, the parasitic absorption reduced drastically, andJphreached 30.23 mA/cm2. Furthermore, by replacing the Si substrate with a glass substrate, the light trapping worked more effectively, and the absorber layer thickness required forJphto saturate was reduced to 1 μm, yielding 32.06 mA/cm2. Based on these simulation results, we manufacturedn+-AZO/p-BaSi2HJSC. The internal quantum efficiency exceeded 30% atλ= 600 nm, meaning that we demonstrated the operation ofn+-AZO/p-BaSi2HJSC for the first time. We investigated origins of small efficiencies compared to those simulated, and found that the passivation of defects in thep-BaSi2layer and the reduction of carrier recombination at thei-ZnO/p-BaSi2interface would significantly improve the solar cell performance.