)study On The Morphology And Performance Of Processed Layer By Layer All-polymer Solar Cells

Organic solar cells（OSC）are considered to be a promising solar cell technology due to many advantages such as flexibility,translucency and light texture.As a branch of OSCs,all-polymer solar cells（All-PSCs）composed of N-type polymers and P-type polymers have attracted extensive attention due to their excellent water,oxygen and mechanical stability.The deposition method of the organic active layer will significantly affect the morphology of the film and thereby determine the performance of the device.In All-PSCs,the strong interaction between donor and acceptor polymers will significantly increase the complexity of morphology control of the active layer,so the traditional blend cast（BC）processing often fails to obtain the ideal morphology;In contrast,Layer-By-Layer（LBL）processing donor and acceptor solutions can more flexibly control the morphology of the active layer.In addition,the structure and properties of the polymer acceptor also have an important impact on the LBL processing technology and the morphology of the active layer.Therefore,based on two acceptors with different backbone structure,this paper studies the influence of LBL on the morphology and performance of All-PSCs.Related work is divided into two parts:In Chapter 3,the influence of BC and LBL processing methods on the photoelectric properties of All-PSCs based on quinone polymer acceptors（Pz DP-T and Pz DP-2FT）and the relationship between the morphology of the LBL active layer and the device performance are studied.Pz DP-T and Pz DP-2FT have good near-infrared absorption and different crystallinity and are used in combination with PBDB-T to construct All-PSCs.For the PBDB-T:Pz DP-T active layer,the hole（μ_h）and electron（μ_e）mobilityof All-PSCs prepared by the BC method is very low,only 3.90,38.0×10^-8 cm² V^-1 s^-1,respectively,which makes the device without photovoltaic response;However,μ_h andμ_e of All-PSCs prepared by LBL method is greatly increased to 5.11 and 15.2×10^-5 cm² V^-1 s^-1,respectively,and the device efficiency is significantly increased to 1.3%.Experiments also show that the use of higher crystallinity Pz DP-2FT as the acceptor can enable the LBL active layer to achieve better phase separation and order,so the device efficiency is further increased to 2.7%.These results indicate that LBL helps to improve the morphology and performance of All-PSCs based on quinoid structure polymer acceptors.In Chapter 4,the effects of BC and LBL methods on the morphology of the active layer and device performance of All-PSCs based on Naphthalene Diimide（NDI）polymer acceptor PTz NDI-T were studied.PTz NDI-T has strong aggregation and good electron mobility,and it is combined with the absorption complementary polymer donor J52-Cl to construct All-PSCs.The normal and inverted devices based on BC have no photovoltaic performance,while the normal and inverted devices based on LBL have a high efficiency of 6.3%and6.0%,respectively.The investigation of the morphology of the active layer shows that the BC active layer displayed excessive distribution of J52-Cl phase and serious interruption of PTz NDI-T phase,leading to extremely lowμ_e and invalid photovoltaic performance.However,the LBL active layer showed a well-distributed bulk heterojunction morphology with bi-continuous interpenetrating network configuration,which can provide efficient charge generation,transportation and collection,and thereby realizing efficient All-PSCs.These results show that LBL has significant advantages in improving the phase separation morphology and device performance of All-PSCs with NDI-based polymer acceptors.