共轭聚合物受体侧链结构修饰与全聚合物光伏电池形貌控制

Organic solar cell (OSC) technology is a promising method to utilize solar energy because of its capability of full solution processed manufacturing, large-scale and low-cost production. However, there is still a big gap to the stage of commercialization due to its low efficiency. The typical bulk heterojunction OSC system, which contains one donor polymer and one fullerene acceptor has been closed to its theoretical limitation. Developing novel high performance electron acceptors is highly demanded. Conjugated polymer is one class of promising materials for photovoltaic devices. Lots of advantages, such as tunable optoelectronic properties, good machinability, and superior long term stability. However, the performance of recently developed conjugated polymer acceptor are much lower than that of fullerenes acceptors. The key issue is that the polymer/polymer blends caused poor phase separation and morphology due to their similar molecular topology, leading a strong charge recombination in photovoltaic devices. To solve these issues, we plan to develop a series of N-type conjugated polymers with polar side chains. The self-assembled behaviors caused by these polar side chains could be a powerful tool to control their phase separation in the prepared films. By the combination of carefully designing the molecular structures and tuning the fabrication process, optimal phase separation is possible to be achieved. The intrinsic relationship of side chain structure, microstructure of blended films, as well as the photovoltaic performance would be deeply investigated. The implementation of this project would provide a broad avenue for the breakthrough of OSC devices. And a high PCE value over 11% is expected to be achieved for all polymer solar cells.

有机光伏器件可通过低温全溶液技术快速、大面积制备，成本低廉，极具商业潜力。然而其较低的光电转化效率尚无法满足商业化需求。基于聚合物/富勒烯的光伏电池效率已经趋近理论极限。为突破其效率壁垒，开发高性能的受体材料至关重要。N-型共轭聚合物因其具有光电性质可调、机械加工性好、稳定性佳等优势，被认为是较为理想的受体材料。然而目前所开发的聚合物受体的性能却远不及富勒烯衍生物，其核心问题在于给受体构型相似，聚合物/聚合物薄膜相分离及形貌难以调控，器件中激子复合严重。本项目拟通过一种侧链修饰手段，即对N-型共轭聚合物侧链进行适当极性化修饰，借助其诱导的分子自组装行为，实现对全聚合物光伏活性层薄膜微观结构的有效调控。本项目的研究内容包括了聚合物受体的设计合成、自组装行为调控及全聚合物光伏器件性能优化。拟通过项目的实施，在高性能聚合物受体材料的研究取得突破，预期得到光电转化效率超过11%的全聚合物光伏电池。

我们设计开发了一系列高性能的光电功能材料与器件，并撰写了与有机光伏电池相关的研究综述。.第一，我们合成了基于宽带隙入硫代巴比妥酸作为弱吸电子端基的非富勒烯受体材料，并制备了相关的有机光伏电池器件。我们通过TDCF测试证明了这些光伏电池的外量子生成效率均超过了90%，这说明这些器件的电子空穴收集均为非场依赖的。我们的研究结果表明了硫代巴比妥酸基团作为构建宽带隙光伏受体分子的潜力。这一设计策略有望适用于叠层光伏电池以及三元共混电池的器件的性能的提升。.第二，我们证实了一种新有机光伏的活性层组分设计思路，即在给受体二元主体结构中引入第三种易于结晶的材料（BTTCN）并同时构建梯度能级排列以促进激子解离与传输。我们证实了在衡量掺杂（0.03化学计量比）即可明显提高光伏电池的器件性能。该研究为三元有机光伏电池的构建提供了新的设计思路。.第三，我们提出了一种独特且简便的方法以可控调节钙钛矿的晶粒尺寸，即通过调节在前驱体溶液中次磷酸铵的浓度来控制晶粒大小并基于此研究了晶粒尺寸对光伏性能、非辐射复合损耗的影响。我们深刻的理解了次磷酸铵的与钙钛矿前驱体的存在的化学反应，揭露了中间体的形成与其作用机制。通过优化掺杂浓度，实现了高开路电压的甲胺铅碘钙钛矿电池光伏器件（1.13V）。.在第四章节中，我们揭示了钙钛矿中路易斯碱钝化分子与有机阳离子间的氢键在影响钝化效果中的关键限制作用，并且能够通过分子设计削弱氢键作用以改善钝化效果，从而最大化辐射复合。基于对钝化机理的深刻理解，我们制备了迄今为止最高效的钙钛矿发光二极管，其峰值外量子效率达到了21.6％。于此同时，我们验证了该二极管在施加反向电压或零偏压情况下同时也可以作为高灵敏度的钙钛矿光探测器。基于这一双功能性质，我们并制备了脉搏检测器以及验证了它们的双向光通讯功能。这些原型机验证了钙钛矿双功能器件在简化集成电路上优势。