The Study Of High-efficiency Flexible Organic Solar Cells

Organic solar cells（OSCs）is a new type of electronic device that converts solar energy into electrical energy.Because of its advantages such as low preparation cost,easy adjustment of photoelectric characteristics,and clean and pollution-free,it has become a research hotspot.In recent years,its development momentum has been rapid.With the continuous improvement and maturity of the working mechanism and preparation process,the photoelectric conversion efficiency（PCE）of the OSCs has exceeded 18%.As we all know,flexible OSCs have more application potential in portable,intelligent wearable devices,photovoltaic integrated buildings and other fields and better conform to the development trend of the intelligent era of technology.However,the traditional transparent electrode indium tin oxide（ITO）is brittle,and the properties requiring high temperature preparation limit its application in flexible OSCs.In this way,it is crucial to find new flexible transparent electrodes with excellent performance to prepare high-efficiency flexible devices to promote the continuous development of flexible OSCs.This thesis focuses on exploring new flexible transparent electrodes:organic conductive polymer solution PEDOT:PSS film and graphene and silver nanowires（NWs）composite（GR&AgNWs）transparent conductive film.The research focuses on the preparation of flexible transparent electrodes,photoelectric performance testing,and the preparation and optimization of flexible devices.The content is mainly as follows:（1）Organic polymer solution PEDOT:PSS was introduced as a flexible transparent electrode.The conductivity of the film with and without CH₃COOH treatment,the transmittance in the spectral range of 300-1000 nm,and the surface morphology of the film were studied.Flexible devices were prepared using PM6:IT-4F as the active layer.The comparison found that when the CH₃COOH-treated film was used as an electrode,and high efficiency after optimized could be achieved,reaching85%of the device efficiency based on the ITO electrode.In addition,the device efficiency based on PET and Glass substrates was comparable.Organic conductive polymer PEDOT:PSS film can be prepared on PET substrate at low temperature and has good adhesion,which helps to promote the large-scale production and application of flexible devices.（2）Flexible OSCs are fabricated using GR&AgNWs as an emerging electrode.The electrode exhibits extremely good optical and electrical properties,environmental stability and mechanical flexibility.To enhance the interface contact,a thin film of highly conductive poly（3,4-ethylenedioxythiophene）:poly-（styrenesulfonate）（PH1000）was used to modify the rough surface of GR&AgNWs.It also avoids work function mismatch between the electrode and interface layer.Therefore,the resultant GR&AgNWs/PH1000 hybrid electrode based on the active layer of PM6:Y6 flexible OSCs yield a high PCE of 13.44%Besides,the devices obtain unique mechanical flexibility.It is possible to retain 85%of the initial PCE after bending one thousand times at a harsh bending radius（r=2 mm）,which is mainly attributed to the flexibility of the GR&AgNWs electrode.This work confirms that GR&AgNWs electrodes are a promising candidate to replace ITO and open an avenue to fabricate excellent performance flexible OSCs for future potential applications due to low cost and more environmental stability and friendliness of the electrode.Through the study of new flexible transparent electrodes and the preparation of high-efficiency flexible devices,the importance of flexible transparent electrodes in the development process of flexible OSCs is further explained,and it also has certain guiding significance for the development of flexible OSCs.The continuous exploration of flexible OSCs is expected to promote the industrialization of OSCs,and it is worth looking forward to the real production and application and benefit mankind.