Versatility and robustness of ZnO:Cs electron transporting layer for printable organic solar cells

Abstract

In this work, the Cs doped sol-gel ZnO film (ZnO:Cs) as efficient and robust electron transporting layer (ETL) in versatile systems of organic solar cells (OSCs) is developed, which can be simply formulated by blending the Cs2CO3 with the Zn(Ac)2 precursor in solutions. The Cs doping significantly increased the ZnO film conductivity and lowered its work function, as unveiled by the conductive atomic force microscope and the ultra-violet photoelectron spectroscopy. Decent device performance enhancements of OSCs with versatile photovoltaic materials, e.g. P3HT:PC61BM, P3HT:ICBA, and PTB7:PC71BM, were observed with the doped ZnO:Cs as the ETL compared with the pristine ZnO ETL. The enhanced device performance was also found in the tandem solar cells. Moreover, the device performance shows little drop with the thickness of the doped ZnO:Cs ETL ranging from 40 to 520 nm, indicating the less thickness dependence for the doped ZnO:Cs ETL. The current work verifies the potential of the Cs doped ZnO as a high performance ETL material for printable OSCs.

ZnO films using a precursor solution irradiated with an electron beam as the cathode interfacial layer in inverted polymer solar cells

“…The conduction band minimum (CBM) was estimated from the VBM and E g (extracted from the Tauc plot). The Ref samples show a W.F of about 4.12 eV, which is similar with that of previously reported sol-gel ZnO, 29 but an E f slightly above the CB is observed in our study. With the increase in irradiation dose from 100, 300 to 500 kGy, the W.F decreases from 3.75, 3.55 to 2.99 eV, respectively.…”

Tackling Energy Loss for High‐Efficiency Organic Solar Cells with Integrated Multiple Strategies

“…Lowering charge transport barriers at the electrode interfaces is crucial for this purpose . To obtain Ohmic contact between the organic semiconductors and interfacial layers, Fermi levels of interlayers need to align with the HOMO of donor or LUMO of acceptor . Figure S7a in the Supporting Information shows the I–V characteristic curves of an inverted device with ZnO nanoparticles (ZnO‐NPs) as the electron transporting layer.…”

Room-Temperature Solution-Processed n-Doped Zirconium Oxide Cathode Buffer Layer for Efficient and Stable Organic and Hybrid Perovskite Solar Cells

“…To overcome intrinsic materials limitations and to improve the overall device performance, an effective strategy is to incorporate charge donating dopants into the host metal oxides (i.e., n-doping) to alter the carrier concentrations and hence the electronic state of the materials. Although several solution-based processing methods for alkali-metal compounds such as cesium carbonate or lithium fluoride have been utilized as n-type dopants to enhance the electrical conduction of metal oxides and improve the interface properties, , the samples generally suffer from degradation issues due to the highly hygroscopic nature of these dopants. An effective approach to circumvent this problem is to incorporate a relatively stable halogen anion such as bromine (Br) or fluorine (F) as the dopant. − These dopants can preferentially substitute the oxygen sites and/or occupy oxygen vacancies, thus contributing to enhanced conductivity.…”