重新思考供体稀释有机太阳能电池中的电荷输运与重组
Rethinking Charge Transport and Recombination in Donor-diluted Organic Solar Cells
AI总结：
研究探讨了供体分数从1%到45%的PM6:Y12体异质结太阳能电池，揭示了形态、电荷输运与重组与器件性能的关系，发现供体稀释不影响光生成，拓扑控制输运和非Langevin重组共同决定性能极限。
摘要：
我们系统地研究了PM6:Y12体异质结太阳能电池，供体分数从1%到45%，将形态、电荷输运和重组与器件性能联系起来。互补的结构和光谱方法揭示，即使在低于5%的供体含量下，PM6网络仍能渗透形成，具有层状堆叠和垂直组成梯度，不会阻碍电荷提取。低供体分数的有效活性层导电性减少符合三维渗透模型，表明电荷输运由网络拓扑结构控制而非显著的渗透阈值。供体分数低于5%时，从非双分子Langevin重组过渡到分散型Smoluchowski型损失。后者也是非双分子的，即涉及总电荷载流子密度的重组。相应地，我们观察到高供体分数下的Langevin减少（主要由电荷对重新解离主导）在低供体分数时发生变化：在这些情况下，非双分子损失率超过Langevin模型的预测。这一阶段与由于拓扑限制的空穴传导增加导致的传输电阻增加相吻合，尽管保留了高电荷生成效率，但填充因子降低。我们的结果表明，强供体稀释在保持光生成的同时，若连续供体网络得以维持，则可有效保护。并揭示了拓扑控制输运和非Langevin重组如何共同定义供体稀释有机太阳能混合物的性能极限。
英文摘要：
We systematically investigate PM6:Y12 bulk-heterojunction solar cells with donor fractions ranging from 1% to 45%, linking morphology, charge transport, and recombination to device performance. Complementary structural and spectroscopic methods reveal that a percolating PM6 network forms even at below 5% donor content, with lamellar stacking and vertical composition gradients that do not hinder the charge extraction. The reduction of the effective active layer conductivity towards low donor fractions obeys a three-dimensional percolation model, indicating that charge transport is governed by network topology rather without a pronounced percolation threshold. A transition from nongeminate Langevin recombination to a dispersive Smoluchowski-type loss occurs below 5% donor fraction. The latter regime is also nongeminate, i.e., pertains to recombination of the total charge carrier density. Correspondingly, we observe that the Langevin reduction in the higher donor fractions - mostly dominated by redissociation of electron-hole pairs after encounter - changes towards low donor fractions: in these cases, the nongeminate loss rate exceeds the prediction of the Langevin model. This regime coincides with increasing transport resistance due to topology-limited hole conduction, leading to reduced fill factors despite a high retained charge-generation efficiency. Our results demonstrate that strong donor dilution preserves photogeneration if a continuous donor network is maintained, and unveil how topology-controlled transport and non-Langevin recombination jointly define the performance limits of donor-diluted organic solar blends.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
