Distinct enhancement of sub-bandgap photoresponse through intermediate band in high dose implanted ZnTe:O alloys.
Distinct enhancement of sub-bandgap photoresponse through intermediate band in high dose implanted ZnTe:O alloys.
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高剂量注入 ZnTe:O 合金中通过中间能带显着增强亚带隙光响应
DOI：
10.1038/srep44399
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发表时间：
2017-03-10
影响因子：
4.6
通讯作者：
Zheng Y
中科院分区：
文献类型：
--
作者：
Li J;Ye J;Ren F;Tang D;Yang Y;Tang K;Gu S;Zhang R;Zheng Y
对高效率中间带(IB)太阳能电池的需求推动了生产高质量IB光伏材料的努力。在这里，我们展示了由高剂量离子注入和脉冲激光熔化制备的高度失配的ZnTe：O合金具有光学活性的IB态和有效的亚带隙光响应，并详细研究了脉冲激光熔化对结构和光学恢复的影响。结构演化和振动动力学研究表明，在脉冲激光熔炼过程中，采用液相外延技术可以显著恢复合金的结构，但激光辐照也加剧了Te在合金中的偏析。光致发光、吸收和光响应特性表明，在价带上方1.8 eV处有一个明显的中间带被光学激活。载流子动力学研究表明，处于IB电子态的载流子具有较长的寿命，这有利于亚禁带能量的光子激发的载流子的快速分离，从而提高了总的转换效率。选择性区域的可重复性注入和激光退火层使高效率的横向结太阳电池得以实现，从而保证了极端的光捕获和有效的电荷分离。
The demand for high efficiency intermediate band (IB) solar cells is driving efforts in producing high quality IB photovoltaic materials. Here, we demonstrate ZnTe:O highly mismatched alloys synthesized by high dose ion implantation and pulsed laser melting exhibiting optically active IB states and efficient sub-gap photoresponse, as well as investigate the effect of pulsed laser melting on the structural and optical recovery in detail. The structural evolution and vibrational dynamics indicates a significant structural recovery of ZnTe:O alloys by liquid phase epitaxy during pulsed laser melting process, but laser irradiation also aggravates the segregation of Te in ZnTe:O alloys. A distinct intermediate band located at 1.8 eV above valence band is optically activated as evidenced by photoluminescence, absorption and photoresponse characteristics. The carrier dynamics indicates that carriers in the IB electronic states have a relatively long lifetime, which is beneficial for the fast separation of carriers excited by photons with sub-gap energy and thus the improved overall conversion efficiency. The reproducible capability of implantation and laser annealing at selective area enable the realization of high efficient lateral junction solar cells, which can ensure extreme light trapping and efficient charge separation.