The effect of surface hydrogenation of metal oxides on the nanomorphology and the charge generation efficiency of polymer blend solar cells

Abstract

In this work, the effect of surface hydrogenation of different metal oxides, in particular molybdenum and tungsten oxides widely used to enhance hole extraction and zinc and titanium oxides widely used to enhance electron extraction, on the nanomorphology and the charge generation efficiency of polymer blend solar cells is investigated. It was found that photoactive layers based on blends using different polymers, in particular poly(3-hexythiophene) (P3HT) and poly[(9-(1-octylnonyl)-9H-carbazole-2,7-diyl)-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT), which normally differ in both morphology and electronic structure, benefited, for both polymers, from deposition on metal oxides with high surface hydrogen content, in the sense that they exhibited improved crystallinity/order as revealed from X-ray diffraction, UV-vis absorption and elipsometric measurements. As a result, increased charge generation efficiencies and reduced recombination losses were measured in solar cells using metal oxides with highly hydrogenated surfaces at bottom electrodes and based on blends of either P3HT or PCDTBT, with a fullerene acceptor, as was verified by transient photocurrent measurements. The power conversion efficiency (PCE) of those cells reached values of 4.5% and 7.2%, respectively, an increase of about 30% compared with the cells using metal oxides with low surface hydrogen content.

Avoiding ambient air and light induced degradation in high-efficiency polymer solar cells by the use of hydrogen-doped zinc oxide as electron extraction material

“…Note that a small reduction in the RMS roughness was also confirmed for 10 nm thin P3HT:PC70BM and P3HT:IC60BA films deposited on HZO layers ( Fig. S6) which indicates that hydrogen present on zinc oxide surface may improve photoactive blend nanomorphology, as previously reported by our group [58]. However, the improvement is not sufficient in order to explain the large enhancement in performance of the devices using HZO material.…”

Surface Modification of ZnO Layers via Hydrogen Plasma Treatment for Efficient Inverted Polymer Solar Cells

“…In Figure a, the XRD measurements of similar P3HT:PC 71 BM blend films deposited on different ZnO substrates are shown. When deposited on the untreated ZnO film, the P3HT:PC 71 BM layer exhibits a weak diffraction peak at 2θ = 5.4°, indicating that P3HT contains a low amount of crystallites with lamellae oriented perpendicularly to the substrate (along the a axis, edge-on orientation). , For the film deposited on the H plasma ZnO film, however, the characteristic diffraction patterns ( h 00) ( h = 1, 2, and 3) of P3HT crystallites become pronounced, as evidenced by the increased intensity of the peak at 2θ = 5.4° and by the appearance of new peaks at 10.6 and 15.9° that are attributed to the primary (100), secondary (200), and tertiary (300) diffraction patterns, respectively, indicating that the stacking perpendicular to the substrate is significantly enhanced. Moreover, the a new diffraction peak appears at 2θ = 23.2°, which corresponds to the π–π stacking direction (010) of P3HT chains in the blend film deposited on the H plasma ZnO, indicative of significant face-on packing (along the b axis).…”

Insight into the influence of defect sites in mixed phase of mesoporous titania nanoparticles toward photocatalytic degradation of 2‐chlorophenol: Effect of light source

“…The Ti 2p spectrum for this catalyst could be fixed into several peaks wherein the peaks at 458.83 (Ti 2p 3/2 ), 462.80 (Ti 2p 1/2 ), and 464.35 (Ti 2p 1/2 ) eV were assigned to TSDs, whereas the peak at 460.10 (Ti 2p 3/2 ) eV was attributed to Ti 4+ . [ 46–48 ] Figure 5b displays the XPS spectra of O 1s with Gaussian fits for MTN in the region of 528–534 eV. The O 1s spectrum of this catalyst verified the presence of OV or Ti 3+ O peaks at 530.05 and 531.35 eV, whereas Ti 4+ O and hydroxide or hydroxyl group (OH − ) peaks at 529.60 and 531.80 eV, respectively.…”