Aqueous Solution Processed Photoconductive Cathode Interlayer for High Performance Polymer Solar Cells with Thick Interlayer and Thick Active Layer

Abstract

An aqueous-solution-processed photoconductive cathode interlayer is developed, in which the photoinduced charge transfer brings multiple advantages such as increased conductivity and electron mobility, as well as reduced work function. Average power conversion efficiency over 10% is achieved even when the thickness of the cathode interlayer and active layer is up to 100 and 300 nm, respectively.

Solution‐Processable Conductive Organics via Anion‐Induced n‐Doping and Their Applications in Organic and Perovskite Solar Cells

“…Besides, metal oxides possess intrinsic lattice defects, which could trap free charges to induce carrier recombination loss of devices . Therefore, additional modification and doping strategies are often used to alleviate these problems, such as the introduction of self‐assembled molecules (SAMs) . Additionally, polyelectrolytes, such as poly[(9,9‐bis(3′‐( N , N ‐dimethylamino)propyl)‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)] bromide (PFN‐Br), polyethylenimine (PEI), and ethoxylated polyethylenimine (PEIE) have been used as cathode interfacial materials to induce strong interfacial dipoles for adjusting work functions (WFs) of electrodes.…”

Controlled self-aggregation of perylene bisimide and its application in thick photoconductive interlayers for high performance polymer solar cells

“…perylene bisimide (PBI), were doped into ZnO thin films to achieve photoconductive cathode interlayers, which possess rather high conductivity under sunlight irradiation, the working condition of PSCs, due to the photoinduced electron transfer from PBI molecules to ZnO. [23][24] Organic dye molecules possess large extinction coefficients over a wide wavelength range, while ZnO shows fast electron transport efficiency. The organic-inorganic hybridized photoconductive materials take advantage of inherent features of both organic and inorganic materials simultaneously, but still remain challenging to achieve molecularly dispersed system due to the easy phase separation.…”

Hybrid Photoconductive Cathode Interlayer Materials Composed of Perylene Bisimide Photosensitizers and Zinc Oxide for High Performance Polymer Solar Cells

“…[17] The devices showed diode behavior with low current in dark, whereas the I-V curve showed a linear relationship with high current under AM 1.5G 1000 W m −2 illumination (the working condition for i-PSCs). The change of the I-V curve implies that the ZnO:PBI films are modulated from semiconductor in dark to conductor under illumination with the electrical conductivities determined to be 4.5 × 10 −3 S m −1 for ZnO:PBI-H and ≈ 6 × 10 −3 S m −1 for ZnO:PBI-Py (Figure 3a).…”

“…As references, devices were also fabricated with pure ZnO as the cathode interlayers. [17,20] When using a 100 nm thick thieno[3,4-b]thiophene/benzodithiophene (PTB7): [6,6]-phenyl C71 butyric acid methyl ester (PC 71 BM) as the active layer, the device based on ZnO:PBI-H cathode interlayer exhibited a PCE of 9.0% with a Voc of 0.75 V, a Jsc of 17.2 mA cm −2 , and a FF of 70.4%, which is a significant improvement compared to the reference device using pure ZnO as the cathode interlayer (PCE of 7.4%, Voc of 0.73 V, Jsc of 15.3 mA cm −2 and FF of 67.3%). Accordingly, all parameters Voc, Jsc, and FF are simultaneously enhanced relative to those of the devices based on pure ZnO.…”

“…[5b] To overcome the relatively low conductivity that limits the thickness of the cathode interlayers, photoconductive cathode interlayers composed of ZnO and organic photosensitizers have been developed most recently. [17] The chemical structures of the successful organic dye photosensitizers PBI-H and PBI-Py are shown in Figure 2a. These PBI dyes bear four bulky substituents at bay areas that are introduced to enhance their otherwise extremely low solubility.…”