Simultaneous morphological stability and high charge carrier mobilities in donor-acceptor block copolymer/PCBM blends

Abstract

Donor-acceptor block copolymers (BCP), incorporating poly(3-hexylthiophene) (P3HT), and a polystyrene copolymer with pendant fullerenes (PPCBM) provide desired stable nanostructures, but mostly do not exhibit balanced charge carrier mobilities. This work presents an elegant approach to match hole and electron transport in BCP by blending with molecular PCBM without causing any macrophase separation. An insufficient electron mobility of PPCBM can be widely compensated by adding PCBM which is monitored by the space-charge limited current method. Using X-ray diffraction, atomic force microscopy, and differential scanning calorimetry, we verify the large miscibility of the PPCBM:PCBM blend up to 60 wt % PCBM load forming an amorphous, molecularly mixed fullerene phase without crystallization. Thus, blending BCP with PCBM substantially enhances charge transport achieving an electron mobility of l e 5(3.2 6 1.

Role of PCBM in the Suppression of Hysteresis in Perovskite Solar Cells

“…This result implies that the diffusion of PCBM molecules into the perovskite layer is crucial to the elimination of hysteresis in PSCs, consistent with the requirement of thermal annealing to passivate the defects and decrease the trap density in the perovskite layer. [ 20 ] Here, we note that, the relatively poorer performance of the device with PPCBM is probably caused by its relatively lower electron mobility, [ 26 ] hindering the effective electron extraction by TiO 2 /FTO layer.…”

Ultrathin film heterojunctions by combining solution processing and sublimation for ambipolar organic field-effect transistors

“…The rigidity of the fibers prevents penetration of the NDI-C9 molecules into the P3HT ''phase'' and leads to a distinct phase separation to facilitate the charge transport. 42,43 For this reason, the ambipolar mobilities in these nano-structured bulk-like heterojunction structures were higher in comparison to the planar bilayer heterojunction films obtained solely from solution. In our previous work we reported that hole and electron mobilities were increased by one order of magnitude when P3HT fibrils were surrounded by a PCBM phase.…”

Mechanical Properties of Organic Semiconductors for Stretchable, Highly Flexible, and Mechanically Robust Electronics

“…Despite its importance, the glass transition of many organic semiconductors is not easily determined. The change in heat capacity in the vicinity of T g for organic semiconductors is often too weak to detect by DSC. ,− Other techniques, such as dynamic mechanical analysis (DMA) or variable-temperature ellipsometry (which has been applied to polyolefins , as well as conjugated polymers), are often required. The glass transition can also be predicted computationally, as atomistic and coarse-grained molecular dynamics (MD) simulations have been used to obtain values that are in good agreement with experiment …”