金属氧化物基杂化型聚合物太阳电池研究

以有机共轭聚合物为电子给体和无机纳米结构为电子受体组成的杂化型聚合物太阳电池(HPSC), 是一类新型的光伏器件. HPSC将有机物和无机物的光学、电学和力学等性能集成在一起, 其最显著的优点体现在材料来源丰富、性能互补且可调控、易实现低成本组装及轻便等方面. 金属氧化物纳米结构具有环境友好、可见光区透明且易合成等特点, 是很有发展前景的电子受体材料. 本文首先简要介绍了HPSC电池的研究现状、工作原理、器件结构、和稳态及动态表征方法, 然后重点综述了在基于ZnO和TiO₂纳米结构的HPSC方面的研究进展, 包括载流子传输动力学理论模型、高效电池材料与器件的设计和制备、及纳米结构特性相关的器件性能等. 最后, 对我们的研究成果进行了总结, 并展望了电池的后续研究方向和发展前景.

Hybrid p olymer-based solar cells with metal oxides as the main electron acceptor and transp orter

Hybrid polymer-based solar cells (HPSCs) that use conjugate polymers as electron donor (D) and inorganic semiconductor nanocrystals as electron acceptor (A) are novel photovoltaic devices. HPSCs integrate the properties of organic polymer (flexibility, ease of film formation, high absorption coefficient) and inorganic nanostructures (high electron mobility, high electron affinity, and good stability), and have the extra advantages, such as the rich sources of synthesized nanostructures by wet chemistry, tunable and complementary properties of assembled components, solution-processibility on a large scale at low cost and light-weight, etc. Amongst various inorganic semiconductor materials, the nanostructured metal oxides are the promising electron acceptors for HPSCs, because they are environment-friendly, transparent in visible spectrum and easy to be synthesized. After a brief introduction to the current research status, working principles, device architecture, steady-state and dynamic characterizations of HPSCs, this paper mainly reviews our recent research advances in the HPSCs using ZnO and TiO₂ nanostructures as main electron acceptor and transporter, with emphasis on the theoretical models for charge carrier transport dynamics, design and preparation of efficient materials and devices, and the device performance related with nanostructural characteristics. Finally, the main challenges in the development of efficient HPSCs in basic researches and practical applications are also discussed. The main conclusions from our studies are summarized as follows: (i) IMPS and IMVS are powerful dynamic photoelectrochemical methods for studying the charge transport dynamics in HPSCs, and our theoretical models enable the IMPS to serve as an effective tool for the mechanistic characterization and optimization of HPSC devices. (ii) Using a multicomponent photoactive layer with complementary properties is an effective strategy to achieve efficient HPSCs. (iii) Using the complementary property of components, enhancing the dissociation efficiency of excitons, and improving the transport properties of the acceptor channels with reduced energy loss to increase collection efficiency all are the effective measures to access a high photocurrent generation in HPSCs. (iv) The band levels of components in the photoactive layer of HPSCs are aligned into type II heterojunctions, in which the nanostructured component with the lowest conduction band edge acts as the main acceptor/transporter; the maximum open-circuit voltage (V_oc) in HPSCs is determined by the energy difference between the highest occupied molecular orbital (HOMO) level of conjugated polymer and the conduction band edge of the main acceptor, but the V_oc in practical devices correlates strongly with the quasi-Fermi levels of the electrons in the main acceptor and the holes in the polymer. While passivating the surface defects on the main acceptor, increasing spatial e-h separation, and enhancing the electron density in conduction band of the main acceptor will facilitate the increase in V_oc. (v) There is no direct correlation among V_oc, photogenerated voltage (V_ph) and electron lifetime (τ_e), and they may change in the same or the opposite trend when the same or different factors affect them, therefore one should get insight into the intrinsic factors that influence them when discussing the changes in V_oc, V_{ph} and τ_e that are subject to nanostructural characteristics.