Control of nanomorphology in all-polymer solar cells via assembling nanoaggregation in a mixed solution

Utilizing Benzotriazole and Indacenodithiophene Units to Construct Both Polymeric Donor and Small Molecular Acceptors to Realize Organic Solar Cells With High Open-Circuit Voltages Beyond 1.2 V

Devolopment of organic solar cells with high open-circuit voltage (V_OC) and power conversion efficiency (PCE) simutaniously plays a significant role, but there is no guideline how to choose the suitable photovoltaic material combinations. In our previous work, we developed "the Same-Acceptor-Strategy" (SAS), by utilizing the same electron-accepting segment to construct both polymeric donor and small molecular acceptor. In this study, we further expend SAS to use both the same electron-accepting and electron-donating units to design the material combination. The p-type polymer of PIDT-DTffBTA is designed by inserting conjugated bridge between indacenodithiophene (IDT) and fluorinated benzotriazole (BTA), while the n-type small molecules of BTAx (x = 1, 2, 3) are obtained by introducing different end-capped groups to BTA-IDT-BTA backbone. PIDT-DTffBTA: BTAx (x = 1-3) based photovolatic devices can realize high V_OC of 1.21-1.37 V with the very small voltage loss (0.55-0.60 V), while only the PIDT-DTffBTA: BTA3 based device possesses the enough driving force for efficient hole and electron transfer and yields the optimal PCE of 5.67%, which is among the highest value for organic solar cells (OSCs) with a V_OC beyond 1.20 V reported so far. Our results provide a simple and effective method to obtain fullerene-free OSCs with a high V_OC and PCE.

Effects of incorporating different chalcogenophene comonomers into random acceptor terpolymers on the morphology and performance of all-polymer solar cells

A new family of NDI-based random terpolymers, incorporating a small amount (10%) of different chalcogenophene units (-Fu, -Th, -Se) was synthesized and investigated for all-PSCs.

Tellurophene-Based N-type Copolymers for Photovoltaic Applications

Novel tellurophene-based n-type copolymers are synthesized and characterized with thermal analysis, electrochemistry, optical spectroscopy, and DFT calculations. The copolymers demonstrate reversible interactions with bromine. Through tuning of the building blocks and alkyl chains together with device engineering, the maximum power conversion efficiency of all-polymer solar cells improves from 2.8 to 4.3%, which is supported by photoluminescence, atomic force microscopy, transmission electron microscopy, the space charge limit current method, and exciton dynamic studies. These results suggest that tellurophene-based n-type copolymers are promising electron acceptors for organic solar cells and potential sensor materials for bromine detection.

7.7% Efficient All-Polymer Solar Cells

By controlling the polymer/polymer blend self-organization rate, all-polymer solar cells composed of a high-mobility, crystalline, naphthalene diimide-selenophene copolymer acceptor and a benzodithiophene-thieno[3,4-b]thiophene copolymer donor are achieved with a record 7.7% power conversion efficiency and a record short-circuit current density (18.8 mA cm(-2)).

Pressure-Sensitive Adhesives under the Influence of Relative Humidity: Inner Structure and Failure Mechanisms

Model pressure-sensitive adhesive (PSA) films of the statistical copolymer P(EHA-stat-20MMA), which comprises 80% ethylhexyl acrylate (EHA) and 20% methyl methacrylate (MMA), are studied. The PSA films are stored under different relative humidities from <2% to 96% for 24 h and subsequently investigated concerning the near-surface composition profile by measuring X-ray reflectivity (XRR) and tack performance. For both types of measurements, special custom-made sample environments are used, which ensure constant temperature and relative humidity during the XRR and tack measurements. Different failure mechanisms of the adhesive bond are found by adjusting the relative humidity. XRR measurements evidence enrichment layers in vicinity to and at the surface depending on the provided relative humidity during the postproduction treatment, which also influence the tack performance. This finding is supported by tack measurements using punches with different roughness.

Effect of alkyl-chain branching position on nanoscale morphology and performance of all-polymer solar cells

The improved performance of an all-polymer solar cell was attributed to the well-ordered structure of polymer C3 and nanoscale phase separation in a blend film of the polymer, which resulted from manipulating the alkyl-chain branching position of the polymer.