Liu Yue,Cai Hongkun,Chu Yinhuan,Su Jian,Ye Xiaofang,Ni Jian,Li Juan,Zhang Jianjun
Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is widely used as a hole transport materials in perovskite solar cells, due to a variety of suitable properties. However, the existence of the insulated PSS chain leads to the low electrical conductivity, which should be improved for the further development of inverted perovskite solar cells. In this study, three alcohol solvents were proposed for post-treatment of PEDOT:PSS thin films, which utilized the electrostatic shielding effect of alcohol molecules to promote phase separation of the PEDOT chain and the PSS chain. At the same time, The insulated PSS chain was removed by dissolving in highly hydrophilic alcohols. In the end, we successfully improved the conductivity of PEDOT:PSS thin films. By ethanol solvent treatment, the short-circuit current density of the perovskite solar cell based on glass/ITO/PEDOT:PSS was increased from 15.64 to 17.45 mA/cm 2 , the power conversion efficiency (PCE) reached 11.36%, which was 25% higher than the traditional structure. For flexible devices, a preliminary PCE of 9.20% was achieved.
The poly3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) hole transport layer (HTL) has always played a crucial role in achieving high-efficiency organic solar cells (OSCs) owing to its unique advantages of suitable energy levels and high optical transparency. However, the inherent insulation and easy aggregation property of PSS results in relatively low conductivity and high surface roughness of the PEDOT:PSS film, which is unfavorable for charge transport and the morphology of the top layer. To address these problems, we use PEDOT:PSS diluted in a series of alcoholic solvents and evaluate them on the PM6:Y6 system. Among these, the PM6:Y6 devices using PEDOT:PSS modified with ethanol as the HTL demonstrate the best vertical phase segregation and carrier extraction. In addition, the PEDOT:PSS film with added ethanol also has the smoothest surface compared to those diluted in the other alcoholic solvents. Finally, a high power conversion efficiency of 18.13% was obtained with the PM6:Y6 devices based on PEDOT:PSS modified by ethanol. This work provides a sufficient reference for the alcoholic modification of PEDOT:PSS and also proposes a feasible solution for high-efficiency OSCs.
Hypothesis Transfer of chemical-vapor-deposition (CVD) grown monolayer graphene from one substrate to another requires a transfer agent. The transfer agent usually needs to be removed by washing with organic solvent such as acetone or high temperature annealing, which is harmful to the structure integrity and intrinsic property of a graphene film. Here, we propose the use of camphor as a transfer agent to transfer monolayer graphene onto a target dielectric substrate, which bypasses these demanding steps and only needs the common alcohol solvent rinsing. Experiments To facilitate a crack-free graphene transfer, the proposed approach allows the camphor supported polycrystalline graphene to be rationally fastened with a thickened and solidified edge bead (i.e. camphor oil-filled boundary). A layer of camphor was first deposited onto a graphene/copper surface. The backside copper substrate was then etched away, whilst the camphor/graphene bilayer was placed onto a SiO 2 /Si substrate. Finally, the camphor remaining on the camphor/graphene/SiO 2 /Si sublimed into a vapor. The graphene/SiO 2 stack was then examined by microscopic, spectral and electrical characterization. Findings The results of our examination suggest that the proposed method can guarantee a clean and damage-free graphene transfer. This method is particularly attractive in the application area for nano/micro-electronics, where it provides CVD-grown graphene the ability to be used on wide varieties of substrates that are sensitive to organic solvents and high temperature.
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