Spin-dependent effects in organic solar cells (OSCs) are responsible for tuning the electric current when an external magnetic field is applied. Here, we report the magnetic field effect (MFE) on wide-bandgap (WBG) solar cells based on the polymers PBDT(O)-T1 and PBDT(Se)-T1 blended with PC₇₀BM. Furthermore, we propose an experimental method based on the electrical transport (i–V) measurements to unveil the negative magneto conductance (MC) at small bias. The observed curves in a double-logarithmic scale display a particular S-like shape, independent of the OSC power conversion efficiency (PCE) or MC amplitudes. Additionally, from the slope of the S-like shape curve, it is possible to identify the fullerene concentrations that would result in the minimum MC and the maximum PCE. Our work opens up a door to find more patterns to describe MFE and PCE in polymer–fullerene solar cells, without the application of external magnetic or luminous sources.

中文翻译：

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揭示聚合物-富勒烯太阳能电池中磁场效应的特征形状

当施加外部磁场时，有机太阳能电池（OSC）中的自旋相关效应负责调节电流。在这里，我们报告了基于聚合物PBDT（O）-T1和PBDT（Se）-T1与PC ₇₀ BM混合的宽带隙（WBG）太阳能电池的磁场效应（MFE）。此外，我们提出了一种基于电传输（i – V）测量以揭示小偏置下的负磁电导（MC）。在双对数刻度上观察到的曲线显示出特定的S形形状，与OSC功率转换效率（PCE）或MC振幅无关。另外，从S形曲线的斜率可以确定富勒烯的浓度，该浓度将导致最小的MC和最大的PCE。我们的工作打开了一扇门，以寻找更多的模式来描述聚合物-富勒烯太阳能电池中的MFE和PCE，而无需使用外部磁性或发光源。