Jiangsu Provincial Key Laboratory of Advanced Photonic and Electronic Materials, and School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.
Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra 2601, Australia.
Sci Rep. 2017 Mar 10;7:44399. doi: 10.1038/srep44399.
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.
对高效率中间能带 (IB) 太阳能电池的需求推动了高质量 IB 光伏材料的生产。在这里，我们展示了通过高剂量离子注入和脉冲激光熔化合成的高度失配的 ZnTe:O 合金，表现出光活性 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表明，在脉冲激光熔化过程中通过液相外延实现了 ZnTe:O 合金的显著结构恢复，但激光辐照也加剧了 ZnTe:O 合金中 Te 的分凝。光致发光、吸收和光响应特性证明了位于价带上方 1.8 eV 的明显中间能带被光学激活。载流子动力学表明，IB 电子态中的载流子具有相对较长的寿命，这有利于激发亚带隙能量的光子产生的载流子的快速分离，从而提高整体转换效率。选择性区域注入和激光退火的可重复性能力实现了高效的横向结太阳能电池，这可以确保极端光捕获和有效的电荷分离。
