Research On Highly Efficient And Flexible Stretchable Polymer Solar Cells With Random Buckling

Wearable electronics have become necessary devices in everyone's life,because of their wide application prospects.Along with pursuance towards more comfortable and convenient wearable electronic devices,stretchable wearable electronic devices have aroused wide attention and research.The device used as supplying energy is an absolutely necessary part for application of electronic devices.Of course,stretchable polymer solar cells(stretchable PSCs)have shown great potential as stretchable power generators for applications in stretchable electronics,such as wearable electronics,electronic skins and stretchable displays.Polymer solar cells have many advantages,such as high efficiency,lightweight,pollution-free,flexiblity and so on.However,polymer absorption layers with elasticity have not been fabracated successfully until now,so the intrinsically stretchable PSCs have not been reported by far.Now,all stretchable PSCs are based on the mechanical buckling and spring fiber.Little attention has been paid to stretchable PSCs based on spring fiber because of immaturity of preparation process,amall light-absorbing area and so on.Stretchable PSCs based on the mechanical buckling are most common ones and their principle is that the flexiblity of PSCs is transformed to the tensile strength.The highest efficiency,tensile strain and number of stretching-releasing cycle of reported stretchable PSCs are 4.0%,400%,22,respectively by far.In this dissertation,in order to improve the efficiency and strain of stretchable PSCs,we fabricated stretchable PSC based on efficient active layer of PCDTBT:PC71BM with random buckling.Firstly,the ultrathin transparent flexible substrate was fabricated and its thickness is only about 11 ?m so that the thickness of the whole PSC is less than 11.4 ?m.Then,the stretchable PSCs was fabricated by attaching the ultrathin PSC onto a pre-stretched elastomeric substrate and then releasing the prestrain to form random bucklings.Enhanced flexibility of ultrathin PSCs was beneficial to improve the strain of stretchable PSC.Moreover,We used ultrathin metallic flexible transparent electrode(TCE)to replace commonly PEDOT:PSS electrode,and the sheet resistance of the ultrathin flexible metallic TCE was one order of magnitude lower than the PEDOT:PSS electrodes at the same transmittance,improving short-circuit current.In all,our stretchable PSC's PCE of 5.8% under 70% tensile strain is the largest to date among the reported PSCs.Mechanically robust is a key indicator for the application of stretchable polymer solar cell.In here,the mechanical stability has been improved by inserting a sacrificial layer between the ultrathin PSC and elastomeric support to avoid their direct contact that lead to the damage of bottom electrode.The stretchable PSCs exhibited only small fluctuations in performance after 400 stretching-releasing cycles.This simple and low-cost method is compatible with most PCSs fabrication processes,so that it provided a new way to develop stretchable electronics.