Sharma Punit, Rana Aniket, Waheed Sobia, Pareek Saurabh, Karak Supravat
Organic & Hybrid Electronic Device Laboratory (OHEDL), Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016, India.
Nanotechnology. 2021 Apr 6;32(26). doi: 10.1088/1361-6528/abe1f2.
In this article, the synthesis of phase pure iron pyrite nanocubes (FeSNCs) and their various effects on the charge carrier dynamics and photovoltaic performances of P3HT:PCBM based hybrid bulk-heterojunction solar cells have been studied. The optimum doping concentration of FeSNCs was found to be 0.3 wt%. For the optimally doped devices, the short-circuit current density was found to have improved from 5.47 to 7.99 mA cmleading to an overall cell efficiency improvement from 2.10% to 3.22% as compared to the undoped reference devices. The enhancement in photovoltaic performance is mainly attributed to the formation of localized energy states near the band edges leading to higher carrier generation rate by 72% whereas carrier dissociation probability is also increased by 13%. Urbach energy estimation reveals that the optimally doped devices have achieved a relatively balanced amount of localized states resulting in reduced non-radiative recombination. Such localized defect states formation with FeSNCs doping was also found to have significant influence over the charge carrier dynamics of the active layer. Transient photocurrent and photovoltage studies revealed that FeSNCs assist in faster carrier extraction by reducing the transport time from 1.4 to 0.6s and by enhancing carrier recombination time from 51.7 to 78.9s for the reference and optimum devices respectively. Such an unorthodox approach of defect state assisted efficiency improvement demonstrates the importance of simultaneously understanding the charge carrier dynamics and photovoltaic performance for rational device optimization, and opens new prospects for developing high-efficiency solution processable hybrid devices.
在本文中，研究了纯相黄铁矿纳米立方体（FeSNCs）的合成及其对基于P3HT:PCBM的混合体异质结太阳能电池电荷载流子动力学和光伏性能的各种影响。发现FeSNCs的最佳掺杂浓度为0.3 wt%。对于最佳掺杂的器件，与未掺杂的参考器件相比，短路电流密度从5.47提高到7.99 mA/cm²，导致整体电池效率从2.10%提高到3.22%。光伏性能的提高主要归因于在带边附近形成局域能态，导致载流子产生率提高72%，而载流子解离概率也提高了13%。乌尔巴赫能量估计表明，最佳掺杂的器件实现了相对平衡的局域态数量，从而减少了非辐射复合。还发现，FeSNCs掺杂形成的这种局域缺陷态对活性层的电荷载流子动力学有重大影响。瞬态光电流和光电压研究表明，FeSNCs分别将参考器件和最佳器件的传输时间从1.4降低到0.6 s，并将载流子复合时间从51.7提高到78.9 s，从而有助于更快地提取载流子。这种通过缺陷态辅助提高效率的非传统方法证明了同时理解电荷载流子动力学和光伏性能对于合理器件优化的重要性，并为开发高效溶液可加工混合器件开辟了新前景。
