Two-terminal tandem cell architectures are believed to be an effective way to further improve the power conversion efficiency in solution processed photovoltaics. To design an efficient tandem solar cell, two key issues need to be considered. First, subcells with well-matched currents and complementary absorption characteristics are a prerequisite for high efficiency. Second, identifying the appropriate intermediate layer (IML) to connect the subcells is necessary to minimize the optical and electronic losses. PbS colloidal quantum dots (CQDs) are a notable choice for the subcells due to their low cost, solution processability, and remarkable wide range band gap tunability. Single-layer graphene (Gr) has been proposed to be a promising IML due to its high transparency and conductivity. Here, as a proof of concept, we demonstrate a solution-processed, two-terminal PbS CQDs tandem solar cell employing chemical vapor deposited Gr as the IML. In doing so, we report a PbS CQD cell comprising subcells with bandgaps of 1.4 and 0.95 eV that delivers power conversion efficiency in excess of 7%, substantially higher than that of previously reported CQD tandem cells.

中文翻译：

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使用化学气相沉积石墨烯作为原子薄中间重组层的胶体量子点串联太阳能电池

人们认为，双端串联电池体系结构是进一步提高溶液处理的光伏发电效率的有效途径。为了设计高效的串联太阳能电池，需要考虑两个关键问题。首先，具有良好匹配的电流和互补吸收特性的子电池是高效率的先决条件。其次，必须确定适当的中间层（IML）以连接子电池，以最大程度地减少光学和电子损耗。PbS胶体量子点（CQD）是子电池的一个显着选择，因为它们的成本低，溶液加工性能好，并且具有宽范围的带隙可调性。由于其高透明性和导电性，单层石墨烯（Gr）被认为是有前途的IML。在这里，作为概念证明，我们展示了采用化学气相沉积Gr作为IML的固溶处理的两端PbS CQDs串联太阳能电池。这样做时，我们报告了一个PbS CQD电池，该电池包含带隙为1.4和0.95 eV的子电池，其功率转换效率超过7％，大大高于以前报道的CQD串联电池的功率转换效率。