JIANG ZHI XUAN

Ternary organic solar cells based on nonfullerene 3TP3T‐4F and 3TP3T‐IC guest acceptors and PM:Y6 binary host are investigated. The incorporation of 15% 3TP3T‐4F leads to an impressive efficiency of 16.7% (certified as 16.2%) for PM6:Y6:3TP3T‐4F ternary organic solar cells, higher than that (15.6%) of PM6:Y6:3TP3T‐4F devices, which is mainly ascribed to the compatibility between the third component and the host materials.

Abstract

A ternary structure has been demonstrated as being an effective strategy to realize high power conversion efficiency (PCE) in organic solar cells (OSCs); however, general materials selection rules still remain incompletely understood. In this work, two nonfullerene small‐molecule acceptors 3TP3T‐4F and 3TP3T‐IC are synthesized and incorporated as a third component in PM6:Y6 binary blends. The photovoltaic behaviors in the resultant ternary OSCs differ significantly, despite the comparable energy levels. It is found that incorporation of 15% 3TP3T‐4F into the PM6:Y6 blend results in facilitating exciton dissociation, increasing charge transport, and reducing trap‐assisted recombination. All these features are responsible for the enlarged PCE of 16.7% (certified as 16.2%) in the PM6:Y6:3TP3T‐4F ternary OSCs, higher than that (15.6%) in the 3TP3T‐IC containing ternary devices. The performance differences are mainly ascribed to the compatibility between the third component and the host materials. The 3TP3T‐4F guest acceptor exhibits an excellent compatibility with Y6, tending to form well‐mixed phases in the ternary blend without disrupting the favored bicontinuous transport networks, whereas 3TP3T‐IC displays a morphological incompatibility with Y6. This work highlights the importance of considering the compatibility for materials selection toward high‐efficiency ternary organic OSCs.

Publication date: Available online 19 November 2019

Source: Solar Energy Materials and Solar Cells

Author(s): Yanjie Wu, Cong Chen, He Wang, Wenbo Bi, Zonglong Song, Xinfu Chen, Junjie Jin, Xu Chen, Lin Xu, Qilin Dai, Hongwei Song

Graphical abstract

Publication date: Available online 15 November 2019

Source: Solar Energy Materials and Solar Cells

Author(s): Shina Li, Ruixin Ma, Xing zhao, Jiahui Guo, Yuchun Zhang, Chenchen Wang, He Ren, Yong Yan

Publication date: February 2020

Source: Solar Energy Materials and Solar Cells, Volume 205

Author(s): Yu Kawano, Jakapan Chantana, Takahito Nishimura, Takashi Minemoto

MoS 2 is promising for the next generation of electronic and optoelectronic devices by virtue of its unique optical, electrical and mechanical properties. Bandgap engineering of it is an interesting topic. However, the reported factors including temperature, defect, strain and external electric field are difficult to handle precisely. Here, we demonstrated direct–indirect bandgap transition in monolayer MoS 2 induced by an individual Si nanoparticle. We observed photoluminescence (PL) emission with obvious spectral redshift and broadening in the MoS 2 /Si heterostructures after depositing Si nanoparticles onto the surface of monolayer MoS 2 . Raman spectra of heterostructures show measurable shifts in contrast with the bare MoS 2 . Energy transfer between MoS 2 and Si nanoparticles did not happen, which is demonstrated by scattering spectra of MoS 2 /Si heterostructures. In addition, the natural oxide layer presen...

Nature Chemistry, Published online: 11 November 2019; doi:10.1038/s41557-019-0354-2

A solution-processing step has been used to prepare quantum-well structures that comprise a thin layer of perovskite sandwiched between two layers of conjugated oligothiophene derivatives. The band gap of the resulting 2D hybrid perovskites can be fine-tuned by functionalizing the organic component, which also improves the stability of the system.

Hole transporting layers (HTLs) play a crucial role in the realization of efficient and stable perovskite solar cells (PSCs). Copper phthalocyanine (CuPc) is a promising HTL owing to its thermal stability and favorable band alignment with the perovskite absorber. However, the power conversion efficiency (PCE) of PSCs with a CuPc HTL is still lagging behind highly efficient solar cells. Herein, a p-type tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) is employed as an interlayer between the perovskite and CuPc HTL in all-vacuum deposited PSCs. The F4-TCNQ interlayer improves the conductivity of both MAPbI 3 and CuPc, reduces the shunt pathway and facilitates an efficient photoexcited holes transfer from the valance band of the MAPbI 3 to the LUMO of the F4-TCNQ. Consequently, the best solar cell device with an F4-TCNQ interlayer achieved a PCE of 13.03% with a remarkable improvement in fill factor. Moreover, the device showed superior stability against thermal ...

The nature of precursor solutions not only impacts the nucleation rate and crystallization kinetics of perovskite crystals, but also influences the physical properties of perovskite thin films. This Review presents the comprehensive understanding on the nature of perovskite precursor solutions and the formation mechanism of perovskite thin films from these precursor solutions.

Abstract

The composition, crystallinity, morphology, and trap‐state density of halide perovskite thin films critically depend on the nature of the precursor solution. A fundamental understanding of the liquid‐to‐solid transformation mechanism is thus essential to the fabrication of high‐quality thin films of halide perovskite crystals for applications such as high‐performance photovoltaics and is the topic of this Review. The roles of additives on the evolution of coordination complex species in the precursor solutions and the resulting effect on perovskite crystallization are presented. The influence of colloid characteristics, DMF/DMSO‐free solutions and the degradation of precursor solutions on the formation of perovskite crystals are also discussed. Finally, the general formation mechanism of perovskite thin films from precursor solutions is summarized and some questions for further research are provided.

A simple perovskite solar cell architecture, which is based on dopant‐free electron and hole conductors and carbon back contact deposited at room temperature, is demonstrated. The resulting architecture leads to the fabrication of cheap and highly efficient perovskite solar cells exhibiting unprecedented long‐term operational and UV stability thus hold immense potential for large‐scale deployment.

Abstract

Today's perovskite solar cells (PSCs) mostly use components, such as organic hole conductors or noble metal back contacts, that are very expensive or cause degradation of their photovoltaic performance. For future large‐scale deployment of PSCs, these components need to be replaced with cost‐effective and robust ones that maintain high efficiency while ascertaining long‐term operational stability. Here, a simple and low‐cost PSC architecture employing dopant‐free TiO₂ and CuSCN as the electron and hole conductor, respectively, is introduced while a graphitic carbon layer deposited at room temperature serves as the back electrical contact. The resulting PSCs show efficiencies exceeding 18% under standard AM 1.5 solar illumination and retain ≈95% of their initial efficiencies for >2000 h at the maximum power point under full‐sun illumination at 60 °C. In addition, the CuSCN/carbon‐based PSCs exhibit remarkable stability under ultraviolet irradiance for >1000 h while under similar conditions, the standard spiro‐MeOTAD/Au based devices degrade severely.