angjie Li

Efficient and stable polymer solar cells with solution-processed molybdenum oxide interfacial layer

We report efficient and stable polymer solar cells (PSCs) based on poly(3-hexylthiophene) and various fullerene derivatives using solution processed, cost effective molybdenum oxide (s-MoOx) as an anode interfacial layer. The chemical structure of the obtained s-MoOx was characterized by FTIR and XPS. The s-MoOx layer exhibits high light transmittance and effective hole collection properties. The PSCs with the s-MoOx anode buffer layer show enhanced performance in comparison with PEDOT:PSS modified devices. The power conversion efficiency of the PSC based on P3HT:IC70BA with the s-MoOx anode buffer layer reached 6.57% under an illumination of AM1.5G at 100 mW cm−2. In addition, compared with PEDOT:PSS modified devices, PSCs with the s-MoOx anode buffer layer exhibit a much superior stability and longer lifetime.

High-Performance Polymer Solar Cells with Solution-Processed and Environmentally Friendly CuOx Anode Buffer Layer

Highly efficient polymer solar cells (PSCs) are demonstrated by introducing environmentally friendly CuOx as hole extraction anode buffer layer. The CuOx buffer layer is prepared simply via spin-coating 1,2-dichlorobenzene solution of Copper acetylacetonate on the ITO substrate and thermal transformation (at 80 °C) in air. Remarkable improvements in the open-circuit voltage (Voc) and short-circuit current density (Jsc) of the PSCs could be achieved upon the introduction of CuOx buffer layer. The study about the effect of CuOx interfacial layer on the device resistances demonstrates that insertion of CuOx layer can decrease the whole resistance of the PSCs. For the devices based on P3HT:PCBM, the power conversion efficiency (PCE) was increased from 2.8% (the reference device without buffer layer) to 4.1% via introduction of CuOx hole extraction layer. The PCE of the PSC was further increased to 6.72% when ICBA used as an alternative acceptor to PCBM. The much higher PCE of 7.14% can be achieved by adopting PBDTTT-C, a low band gap conjugated polymer, as donor material. The results demonstrate that CuOx has great potential as a hole extraction material for highly efficient PSCs.

Efficient polymer solar cells with a solution-processed and thermal annealing-free RuO2 anode buffer layer

A new method is developed to prepare RuO2 films through UVO treatment of solution-processed ruthenium(III) acetylacetonate (Ru(acac)3) without thermal annealing. By introducing RuO2 as an anode buffer layer, highly efficient polymer solar cells (PSCs) have been achieved. The resultant RuO2 layer exhibits high light transmittance in the visible range. Remarkable improvements in the short-circuit current density (Jsc) of the PSCs can be achieved upon the introduction of the RuO2 buffer layer. The PSCs with the RuO2 anode buffer layer demonstrate improved photovoltaic performance in comparison with the devices using poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) as the anode buffer layer. The power conversion efficiency (PCE) of the PSCs based on P3HT:PCBM and P3HT:ICBA reaches as high as 4.19% and 7.07%, respectively. An even higher PCE of 7.45% is realized by adopting a new conjugated polymer, PBDTBDD, as the donor. The results demonstrate that RuO2 has great potential as a hole collection material for highly efficient PSCs.

ITO electrode/photoactive layer interface engineering for efficient inverted polymer solar cells based on P3HT and PCBM using a solution-processed titanium chelate

We report efficient inverted polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) using alcohol-soluble titanium (diisopropoxide) bis(2,4-pentanedionate) (TIPD) as an electron selective layer between the indium tin oxide (ITO) electrode and the photoactive layer. The thermally annealed TIPD layer is highly transparent in the visible range and shows effective electron collection ability. By optimizing the electron-collecting layer, the photoactive layer and the hole-collecting layer, the power conversion efficiency (PCE) of the inverted device with the structure ITO/TIPD/P3HT : PCBM/MoO3/Ag reaches 4.10% under the illumination of AM1.5G, 100 mW cm −2 , which is among the highest values for inverted PSCs based on P3HT : PCBM. The PCE of the inverted device is improved in comparison with the conventional device (3.77%) under the same experimental conditions. (Some figures may appear in colour only in the online journal)

Construction of Planar and Bulk Integrated Heterojunction Polymer Solar Cells Using Cross-Linkable D‑A Copolymer

An integrated device architecture was constructed via vertical combination of planar and bulk heterojunctions by solution processing, where a cross-linked D-A copolymer (PBDTTT-Br25) was inserted between a PEDOT:PSS layer and the blended photoactive layer. PBDTTT-Br25 can readily undergo photo crosslinking to form an insoluble robust film via ultraviolet irradiation after solution-deposition, which enables the subsequent solution processing of a photoactive layer on the robust surface. The insertion of a pure PBDTTT-Br25 layer to build an integrated heterojunction could provide an additional donor/acceptor interface, which enables hole transport to the anode without interruption, thereby reducing the charge carrier recombination probability. The power conversion efficiency (PCE) of the polymer solar cell (PSC) with the integrated architecture reaches 5.24% under an AM1.5G illumination of 100 mW/cm(2), which is increased by 65%, in comparison with that of the reference single heterojunction device (3.17%), under the same experimental conditions.