降低全聚合物太阳能电池光伏效率的温度依赖性

Reduction in the temperature coefficient of photovoltaic efficiency in all-polymer solar cells using molecular order

全聚合物太阳能电池(All-PSCs)具有良好的机械稳定性和热稳定性,受到人们的广泛关注.目前,提高全聚合物太阳能电池性能的关键是改善活性层的形貌.本文通过逐层(LBL)工艺,优化了薄膜形貌,实现了更好的电荷产生和传输,增加了激子扩散长度,提高了电荷产量,并抑制了复合损失.此外,本文进一步研究了LBL制备的全聚合物太阳能电池中的激子/电荷行为与温度的依赖性关系.详细的原位光谱测量和光电特性表征表明,独特的形态延长了激子寿命,减少了电荷陷阱,并促进了电荷传输和收集.因此,准双层PM6/PYF-T-o器件的能量转换效率(PCE)显著提高(16.70%).此外,与BHJ器件相比,通过LBL工艺制备的器件,实现了增强的分子有序性,降低了能级混乱度,使得器件填充系数和PCE温度依赖性减弱.本工作为太阳能电池在温度可变环境下的电荷传输行为和光伏性能提供了新的认识,也为其实际应用提供了理论依据.

Controlling the phase morphology of photo-active layers toward satisfactory charge transport with reduced energetic disorder is the key to obtaining targeted efficiencies in organic solar cells(OSCs).On the basis of an all-polymer model system,i.e.,PM6/PYF-T-o,we investigated the effects of phase morphology on temperature-dependent charge car-rier transport and photovoltaic behavior in all-polymer solar cells prepared through a layer-by-layer(LBL)process.The combined in-situ spectroscopic and morphological analyses reveal that the formation of a fibril structure during the self-assembly of donor molecules and the favorable pure phase of a polymeric acceptor component could promote charge trans-port.Such morphological features reduce the thermal activa-tion energy(Ea)for the carriers.The LBL-processed PM6/PYF-T-o solar cells exhibit a surprisingly small temperature coef-ficient of power conversion efficiency(PCE),i.e.,upon cooling the device to 215 K,the PCE remains at 94.0%of the value at ambient room temperature(RT=298 K)(PCE of 15.65%at 215 K and 16.70%at RT).This study offers an attractive ap-proach for mediating carrier transport and photovoltaic per-formance in OSCs toward applications in a temperature-variable environment.