High-Efficiency Silicon Heterojunction Solar Cells by HWCVD
High-Efficiency Silicon Heterojunction Solar Cells by HWCVD
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HWCVD 高效硅异质结太阳能电池
DOI：
10.1109/wcpec.2006.279723
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
H. Branz
中科院分区：
文献类型：
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作者：
T. Wang;E. Iwaniczko;M. Page;Qi Wang;Y. Xu;Y. Yan;D. Levi;L. Roybal;R. Bauer;H. Branz
本文报道了用热线化学气相沉积法（HWCVD）制备硅异质结（SHJ）太阳能电池的研究进展。一个确认的18.2%的效率在p型织构晶片上已经实现了基于a-Si：H发射极和背接触的表面钝化以及填充因子的改进。高开路电压（Voc）的主要目标是通过正面a-Si：H/c-Si异质结优化、通过用背面c-Si/a-Si：H异质结代替常规Al合金或P扩散背面场以及通过在织构化硅晶片上保持优异的表面钝化来实现。我们首先在具有Al背表面场（BSF）接触的p型太阳能电池上获得652 mV的Voc，其中前a-Si：H（n/i）异质结发射极。然后，高温Al-BSF被低温HWCVD沉积的a-Si：H（i/p）层成功地替代作为背接触。寿命测量表明表面复合速度（SRV）降低到~15 cm/sec。采用a-Si：H（n/i）前发射极和a-Si：H（i/p）背接触双异质结SHJ太阳能电池结构获得了676 mV的较高Voc，表明纹理化p晶片的上级背表面钝化。在n型硅晶片上，我们使用a-Si：H（p/i）前发射极和a-Si：H（i/n）背接触，以实现711 mV的Voc，这是迄今为止通过HWCVD技术获得的最高电压。使用非晶相材料作为背接触也获得了良好的填充因子。当不同a-Si：H层之间存在掺杂交叉污染或与TCO接触的p型a-Si：H层掺杂浓度不足时，I-V曲线呈S形
We report progresses in the development of silicon heterojunction (SHJ) solar cells by hot-wire chemical vapor deposition (HWCVD). A confirmed 18.2% efficiency on a p-type textured wafer has been achieved based on improvements in surface passivation by a-Si:H emitter and back contact as well as in fill factor. The primary objective of high open-circuit voltage (Voc) is achieved by front a-Si:H/c-Si heterojunction optimization, by replacing a conventional Al-alloyed or P-diffused back-surface field with a back c-Si/a-Si:H heterojunction, and by maintaining excellent surface passivation on textured silicon wafers. We first obtain a Voc of 652 mV with a front a-Si:H(n/i) heterojunction emitter on p-type solar cells with an Al back-surface-field (BSF) contact. The high-temperature Al-BSF is then successfully replaced by low-temperature HWCVD-deposited a-Si:H(i/p) layers as the back contact. Lifetime measurement shows the surface recombination velocity (SRV) is reduced to ~15 cm/sec. A higher Voc of 676 mV is obtained with an a-Si:H(n/i) front-emitter and a-Si:H(i/p) back-contact double-heterojunction SHJ solar cell structure, indicating superior back-surface passivation of the textured p-wafer. On n-type silicon wafers, we use an a-Si:H(p/i) front emitter and an a-Si:H(i/n) back contact, to achieve a Voc of 711 mV, the highest voltage obtained by the HWCVD technique so far. Good fill factors are also obtained using the amorphous-phase materials as the back contacts. S-shaped I-V curves are observed if doping cross-contamination are present among different a-Si:H layers or doping level is not enough in the TCO-contacting p-type a-Si:H layer