Controlling the Morphology and Efficiency of Hybrid ZnO:Polythiophene Solar Cells Via Side Chain Functionalization

Abstract

The efficiency of polymer – metal oxide hybrid solar cells depends critically on the intimacy of mixing of the two semiconductors. The effect of side chain functionalization on the morphology and performance of conjugated polymer:ZnO solar cells is investigated. Using an ester‐functionalized side chain poly(3‐hexylthiophene‐2,5‐diyl) derivative (P3HT‐E), the nanoscale morphology of ZnO:polymer solar cells is significantly more intimately mixed compared to ZnO:poly(3‐hexylthiophene‐2,5‐diyl) (ZnO:P3HT), as evidenced experimentally from a 3D reconstruction of the phase separation using electron tomography. Photoinduced absorption reveals nearly quantitative charge generation for the ZnO:P3HT‐E blend but not for ZnO:P3HT, consistent with the results obtained from solving the 3D diffusion equation for excitons formed in the polymer within the two experimental ZnO morphologies. For thin ZnO:P3HT‐E active layers (∼50 nm) this yields a significant improvement of the solar cell performance. For thicker cells, however, the reduced hole mobility and a reduced percolation of ZnO pathways hinders charge carrier collection, limiting the power conversion efficiency.

Optimizing the performance of inverted type hybrid organic solar cell based on ZnO/P3HT with various polymer deposition parameters

“…Figure 5 shows the thickness of P3HT layer on top of ZnO NRAs with various spin coating speeds. The active layer thickness decreased significantly as the spin coating speed increased, which is consistent with previous reports [23,24]. It is believed that the reduction of P3HT top layer at 1000 rpm could improve the hole transportation towards the Ag electrode, as suggested by the lower R s .…”

Hybrid Photovoltaics – from Fundamentals towards Application

“…In this regard, Oosterhout et al studied the distribution of ZnO nanoparticles in an ester functionalized P3HT and the evolution of morphology of such a system with TEM nanotomography. [127] Other examples featured blends of ZnO nanoparticles with P3HT carrying carboxylic acids on the side chains or thermocleavable side groups [128][129][130] or pre-prepared robust mesoporous TiO 2 structures filled with functionalized P3HT. [131] It was also demonstrated that the crystallization of carboxylic acid end-group functionalized P3HT can be utilized for a morphology controlled atomic layer deposition of ZnO on a nanoscale in a precise manner.…”

Hybrid solar cells of conjugated polymers metal-oxide nanocrystals blends; state of the art and future research challenges in Indonesia

“…Moreover, they are environmentally more stable than organic materials. Various inorganic nanocrystals such as CdS [27], CdSe [28], CdTe [29], PbS [30], TiO 2 [31][32] and ZnO [33][34][35][36], have been successfully applied as n-type semiconductor to solution processed BHJ solar cells.…”