Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826, Republic of Korea.
Inter-University Semiconductor Research Center, Seoul National University, Seoul, 08826, Republic of Korea.
Sci Rep. 2017 May 16;7(1):1942. doi: 10.1038/s41598-017-02181-6.
Multilayer structures involving solution-deposited polymer films are difficult to fabricate, not allowing for unrestricted designs of polymer-based optoelectronic devices required for maximizing their performance. Here, we fabricate a hybrid organic tandem solar cell whose top and bottom subcells have polymer:fullerene and small molecules active layers, respectively, by a solvent-free process based on transferring the polymer:fullerene layer from an elastomeric stamp onto a vacuum-deposited bottom subcell. The interface between small-molecule and transferred polymer:fullerene layers is void-free at the nanoscale, allowing for efficient charge transport across the interface. Consequently, the transfer-fabricated tandem cell has an open-circuit voltage (V ) almost identical to the sum of V values for the single-junction devices. The short-circuit current density (J ) of the tandem cell is maximized by current matching achieved by varying the thickness of the small-molecule active layer in the bottom subcell, which is verified by numerical simulations. The optimized transfer-fabricated tandem cell, whose active layers are composed of poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b']dithiophene-2,6-diyl]]:[6,6]-Phenyl-C-butyric acid methyl ester and Di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane:C, has V = 1.46 V, J = 8.48 mA/cm, a fill factor of 0.51, leading to the power-conversion efficiency of 6.26%, the highest among small molecule-polymer:fullerene hybrid tandem solar cells demonstrated so far.
多层结构涉及溶液沉积聚合物膜，难以制造，不允许对最大化其性能所需的基于聚合物的光电设备进行不受限制的设计。在这里，我们通过基于将聚合物：富勒烯层从弹性体印章转移到真空沉积的底子电池上来制造混合有机串联太阳能电池，其顶子和底子电池分别具有聚合物：富勒烯和小分子活性层。在纳米尺度上，小分子和转移的聚合物：富勒烯层之间的界面没有空隙，允许有效电荷在界面上传输。因此，转移制造的串联电池的开路电压（V ）几乎与单结器件的 V 值之和相同。通过改变底子电池中小分子活性层的厚度来实现电流匹配，可以最大化串联电池的短路电流密度（J ），这通过数值模拟得到了验证。优化的转移制造的串联电池，其活性层由聚[2,1,3-苯并噻二唑-4,7-二基[4,4-双（2-乙基己基）-4H-环戊[2,1-b:3,4-b']二噻吩-2,6-二基]]：[6,6]-苯并[C]1,3,2-二恶噻唑-4,7-二酮：甲基酯和二-[4-（N,N-二对甲苯基-氨基）-苯基]环己烷：C 组成，具有 V = 1.46 V，J = 8.48 mA/cm，填充因子为 0.51，导致功率转换效率为 6.26%，是迄今为止展示的小分子-聚合物：富勒烯混合串联太阳能电池中最高的。
