Effect of Crystallinity Modulation between Electron Transport Layer and Photo‐Generation Materials on ZnO‐Based Polymer Solar Cells

Abstract

As one of the most widely used electron transport layers (ETLs) for inverted polymer solar cells (PSCs), ZnO has great effect on the growth of photo‐generated layer. In this work, the ZnO‐based PSCs with the compositional blend of PffBT4T‐2OD: PCBM and PTB7‐Th: PCBM are fabricated to investigate the crystallinity modulation effect (CME) between electron transport layer and photo‐generation materials. The results showed that both the high crystallinity PffBT4T‐2OD: PCBM processed on the large nanoparticles ZnO and the low crystallinity PTB7‐Th: PCBM processed on small nanoparticles ZnO exhibit excellent photovoltaic performances. By verifying the combination of ZnO nanoparticles with photo‐generation materials, it proves that the CME can result in a smooth photo‐generated layer surface to ensure efficient electron transport as well as collection with suppressed bimolecular recombination, leading to the increase of photocurrent and the improvement of inverted PSCs performance accordingly.

Quantifying the optimal thickness in polymer:fullerene solar cells from the analysis of charge transport dynamics and photoabsorption

“…PCPDTBT:PC 71 BM shows the lowest m 0 e ¼ 2.8 Â 10 À3 cm 2 V À1 s À1 and the lowest m 0 h ¼ 6.9 Â 10 À4 cm 2 V À1 s À1 with the imbalanced m 0 e /m 0 h ¼ 4.1. The sequence of m 0 (hole and electron) qualitatively matches that of reported L opt values (270-300 nm for PffBT4T:PCBM, [46][47][48] 150-190 nm for P3HT:PCBM, 49-53 75-100 nm for PCPDTBT:PC 71 BM), [54][55][56][57] indicating the qualitative relationship between carrier mobility and L opt . In all three BHJs, m TOF shows a negative dependence on E, which may result from charge carriers being driven into a more disordered transport route under the increased E. 58 The normalized TRMC transients simultaneously recorded with TPC are shown in Fig.…”

“…8a-c. The simulated J-V curves are in good agreement with the experimental data of P3HT:PCBM, [49][50][51][52][53]73 PffBT4T:PCBM, [46][47][48]73 and PCPDTBT:PC 71 BM, 54,55 showing that the calculation results are reasonable. Fig.…”

“…(b) The calculated L opt as a function of external electric field strength. The coloured region shows the reported L opt range in experiments [46][47][48][49][50][51][52][53][54][55][56][57].…”

Modification of the SnO2 Electron Transporting Layer by Using Perylene Diimide Derivative for Efficient Organic Solar Cells

“…Being inserted between the electrode and active layer, the CTL can decrease the interfacial barrier and adjust the mismatched energy levels, thus facilitating charge carrier collection and transportation (Hsieh et al, 2010;. Currently, an n-type metal oxide, namely, zinc oxide (ZnO), has been widely utilized as the material of the electron transporting layer (ETL) for OSCs because of its matched energy level, good conductivity, high optical transparency, and solution processability (White et al, 2006;Kyaw et al, 2008;Wang et al, 2015;Zhang et al, 2019;Zheng et al, 2019;Fan et al, 2020). However, when placed under ambient sun illumination, ZnO can absorb a large proportion of ultraviolet light, which brings about the degradation of the organic active layer and thus hampers the performance of OSCs (Jiang et al, 2019).…”

Techniques to Facilitate 3D Analysis of Self‐Organized Nanostructure Mechanism in Polymer/Fullerene Bulk Heterojunction Device

“…[ 10–12 ] While there exists a good body of information relating to fullerene/polymer composition ratios, [ 13–15 ] pre/post fabrication processes techniques, [ 16–18 ] choice of solvent, and additives [ 19–21 ] comparatively less attention has been made to the nanostructure formation of these materials. [ 22–24 ] Specifically, as these materials are solution processed, the domain size, crystallinity, and donor/acceptor interfaces are much more dependent on the fabrication process as well as its composition ratios. [ 25–30 ] Furthermore, to date very little information is available in relation to the nanostructure mechanisms of the polymer/fullerene in bulk heterojunction devices in particular experimental techniques to reveal polymer orientation in relation to the fullerene presence.…”