The Active Layer Morphology Control Of Non-fullerene Organic Solar Cells And Study On The Ternary Devices Performance

At present,the main energy source of human comes from the supply of oil and natural gas.With the rapid development of human society,the air pollution caused by high consumption of fossil energy is becoming more and more serious.It was inevitable to promote the development and application of green renewable energy as account of the non-renewable fossil energy.Solar energy is a kind of inexhaustible energy source,meanwhile,the photovoltaic power generation has the advantage of low consumption,environmental protection and sustainability.So it would be an effective way to solve the energy crisis in the event of realizing the sunlight efficiently utilization.The organic solar cell（OSC）was supposed as the most promising solar cell as the advantage of light weight,low cost,semi-transparency and flexible.To date,the power conversion efficiency（PCE）of single hetero-junction OSC has exceeded 15%^[1,2],but the commercial production is still some way off.Therefore,the study on improving the performance of OSCs is still one of the most important topics.The first chapter of this dissertation described the development,working mechanism and device parameters of OSCs.The second chapter introduced the fabrication processes,measurements and optimization methods of OSCs.In chapter 3,we investigated the types of solvents and volume fraction of DIO how to effect on the morphology of active layer and studied the performance differences between the corresponding devices.We used PTB7-Th as donor and F8IC as acceptor to fabricate inverted structure OSCs.The measurements showed that the solvent play a remarkable role in the morphology and thickness of the films.Subsequently,the effects of different volume fraction of DIO on the morphology of PTB7-Th:F8IC blend films were studied,in order to summarize the relationship between solvent,morphology and device performance.In chapter 4,we fabricated PTB7-Th:F8IC:PC₇₁BM ternary OSCs to compensate for the absorption spectrum defects of binary device.The J_sc of the device can increased effectively as these materials have complementary optical absorption.The measurement of AFM shown that the addition of PC₇₁BM can improve the morphology.The efficiency of the devices was increased from 10.13%to 12.41%,which benefit from the enhancement of J_scc and FF.Under the condition of optimal donor-acceptor ratio,ternary OSC exhibits better optical absorption,higher carrier mobility and better active layer morphology.In chapter 5,the PBDB-T:PC₇₁BM:IT-M ternary OSCs was fabricated successfully.The tunable V_oc of devices is realized by adjusting the weight ratio of IT-M in acceptors.The addition of IT-M could suppress the recombination of charge carriers effectively and improve the electrical transmission pathway.Under the illumination of AM 1.5G,the power conversion efficiency of the best device was 11.35%,which has significantly optimized optical and electrical performance.