Carrier transport layers of tin-based perovskite solar cells

Abstract

To avoid environmental pollution caused by lead, the tin-based perovskite solar cells have become a research hotspot in the photovoltaic field. Numerical simulations of tin-based perovskite solar cells are conducted by the solar cell simulation software, SCAPS-1D, with different electron transport layers and hole transport layers. And then the performances of perovskite solar cells are compared with each other and analyzed on different carrier transport layers. The results show that band alignment between the carrier transport layer and the perovskite layer are critical to cell performances. A higher conduction band or electronic quasi-Fermi level of electron transport layer can lead to a higher open circuit voltage. Similarly, a lower valence band or hole quasi-Fermi level of hole transport layer can also promote a higher open circuit voltage. In addition, when the conduction band of electron transport layer is higher than that of the absorber, a spike barrier is formed at the interface between the electron transport layer and perovskite layer. Nevertheless, a spike barrier is formed at the interface between the perovskite layer and the hole transport layer if the valence band of hole transport layer is lower than that of the absorber. However, if the conduction band of electron transport layer is lower than that of the absorber or the valence band of hole transport layer is higher than that of the absorber, a cliff barrier is formed. Although the transport of carrier is hindered by spike barrier compared with cliff barrier, the activation energy for carrier recombination becomes lower than the bandgap of the perovskite layer, leading to the weaker interface recombination and the better performance. Comparing with other materials, satisfying output parameters are obtained when Cd<sub>0.5</sub>Zn<sub>0.5</sub>S and MASnBr<sub>3</sub> are adopted as the electron transport layer and the hole transport layer, respectively. The better performances are obtained as follows: <i>V</i><sub>oc</sub> = 0.94 V, <i>J</i><sub>sc</sub> = 30.35 mA/cm<sup>2</sup>, FF = 76.65%, and PCE = 21.55%, so Cd<sub>0.5</sub>Zn<sub>0.5</sub>S and MASnBr<sub>3</sub> are suitable carrier transport layer materials. Our researches can help to design the high-performance tin-based perovskite solar cells.

Top cell design and optimization of all-chalcopyrite CuGaSe₂/CuInSe₂ two-terminal tandem solar cells

“…第一性原理计算研究已经普遍应用于材料科 学的研究 [41] , 其可靠性已受到广泛认可, 通过第一 性原理计算能够越来越准确地获得材料的电子结 构及相对应的宏观性能参数, 而这些参数能够作为 太阳能电池器件数值模拟的输入参数. 进一步进行 太阳能电池器件的数值模拟, 可获得与电池器件实 验测试直接对比的结果, 并确定影响其效率的主要 因素, 其中SCAPS-1D是当前使用最为广泛的器 件模拟软件之一 [42] .…”

Theoretical analysis of GaN-based semiconductor in changing performanc of perovskite solar cell

“…为光照前电池处于热平衡状态时的能带图，取费米能级为能量零点。根据 Andersons 能带 规则 [28] ，公式(8)为 GaN 层与活性层异质结处的导带偏移值ΔE c ，ΔE c 会影响载流子在界 面上复合强弱，甘等人 [29] 研究表明当在界面处形成"cliff"结构时，流子复合的激活能为 E a ETL = E g active layer -|ΔE c |, E g active layer 为活性层的带隙值，E a ETL 表征了载流子在界面复合的 强弱，E a ETL 越大，V oc 越大，因此适当的ΔE c 有助于电池性能的提升 [30] 。以 GaN 为电子传 输层的导带偏移值ΔE c =-0.05eV，活性层/GaN 导带界面形成较小的能带悬崖(cliff)，减小 了界面复合，使得开路电压增加，同时氮化镓的加入，电池内置电场增加，有利于活性层产 生的光生电子向 GaN 层传输 [31][32][33][34] , 并提高电池的效率，这与 Shuo Lin 等人 [13] 的模拟结果 是一致的。…”