Steacie Institute for Molecular Sciences, National Research Council of Canada , Ottawa, Ontario K1A0R6, Canada.
ACS Appl Mater Interfaces. 2011 May;3(5):1511-20. doi: 10.1021/am200081m. Epub 2011 Apr 8.
Homogeneously alloyed PbSe(x)S(1-x) nanocrystals (NCs) with their excitonic absorption peaks in wavelength shorter than 1200 nm were developed for photovoltaic (PV) applications. Schottky-type solar cells fabricated with our PbSe₀.₃S₀.₇ NCs as their active materials reached a high power conversion efficiency (PCE) of 3.44%, with an open circuit voltage (V(oc)) of 0.49 V, short circuit photocurrent (J(sc)) of 13.09 mA/cm², and fill factor (FF) of 0.54 under Air Mass 1.5 global (AM 1.5G) irradiation of 100 mW/cm². The syntheses of the small-sized colloidal PbSe(x)S(1-x) NCs were carried out at low temperature (60 °C) with long growth periods (such as 45 min) via a one-pot noninjection-based approach in 1-octadecene (ODE), featuring high reaction yield, high product quality, and high synthetic reproducibility. This low-temperature approach employed Pb(oleate)₂ as a Pb precursor and air-stable low-cost thioacetamide (TAA) as a S source instead of air-sensitive high-cost bis(trimethylsilyl)sulfide ((TMS)₂S), with n-tributylphosphine selenide (TBPSe) as a Se precursor instead of n-trioctylphosphine selenide (TOPSe). The reactivity difference of TOPSe made from commercial TOP 90% and TBPSe made from commercial TBP 97% and TBP 99% was addressed with in situ observation of the temporal evolution of NC absorption and with ³¹P nuclear magnetic resonance (NMR). Furthermore, the addition of a strong reducing/nucleation agent diphenylphosphine (DPP) promoted the reactivity of the Pb precursor through the formation of a Pb-P complex, which is much more reactive than Pb(oleate)₂. Thus, the reactivity of TBPSe was increased more than that of TAA. The larger the DPP-to-Pb feed molar ratio, the more the Pb-P complex, the higher the Se amount in the resulting homogeneously alloyed PbSe(x)S(1-x) NCs. Therefore, the use of DPP allowed reactivity match of the Se and S precursors and led to sizable nucleation at low temperature so that long growth periods became feasible. The present study brings insight into the formation mechanism of monomers, nucleation/growth of colloidal composition-tunable NCs, and materials design and synthesis for next-generation low-cost and high-efficiency solar cells.
具有 1200nm 以下激子吸收峰的均匀合金化 PbSe(x)S(1-x)纳米晶体 (NCs) 被开发用于光伏 (PV) 应用。用我们的 PbSe₀.₃S₀.₇ NCs 作为活性材料制造的肖特基型太阳能电池达到了 3.44%的高功率转换效率 (PCE)，开路电压 (Voc) 为 0.49V，短路光电流 (J(sc)) 为 13.09mA/cm²，填充因子 (FF) 在 100mW/cm² 的空气 1.5 全球 (AM 1.5G) 辐照下为 0.54。小尺寸胶体 PbSe(x)S(1-x) NCs 的合成在低温 (60°C) 下进行，通过在 1-十八烯 (ODE) 中的一锅非注射方法进行，具有高反应产率、高质量产品和高合成重现性，生长周期长 (如 45 分钟)。该低温方法使用 Pb(油酸)₂作为 Pb 前体，空气稳定且低成本的硫代乙酰胺 (TAA) 作为 S 源，而不是空气敏感且成本高的双 (三甲基硅基) 硫化物 ((TMS)₂S)，使用 n-三丁基膦硒 (TBPSe) 作为硒前体，而不是 n-三辛基膦硒 (TOPSe)。用原位观察 NC 吸收的时间演化和用 ³¹P 核磁共振 (NMR) 解决了商业 TOP 90% 的 TOPSe 和商业 TBP 97%和 TBP 99%的 TBPSe 的反应性差异。此外，添加强还原剂/成核剂二苯基膦 (DPP) 通过形成 Pb-P 配合物增加了 Pb 前体的反应性，该配合物比 Pb(油酸)₂更具反应性。因此，TBPSe 的反应性增加超过了 TAA。DPP 与 Pb 的进料摩尔比越大，形成的 Pb-P 配合物越多，最终均匀合金化 PbSe(x)S(1-x) NCs 中的 Se 量就越高。因此，使用 DPP 允许 Se 和 S 前体的反应性匹配，并导致在低温下大量成核，从而使长生长周期成为可能。本研究深入了解了单体的形成机制、胶体组成可调 NC 的成核/生长以及下一代低成本、高效率太阳能电池的材料设计和合成。
