Recent progress concerning inorganic hole transport layers for efficient perovskite solar cells (original) (raw)

Progress in hole-transporting materials for perovskite solar cells

Journal of Energy Chemistry, 2018

In recent years the photovoltaic community has witnessed the unprecedented development of perovskite solar cells (PSCs) as they have taken the lead in emergent photovoltaic technologies. The power conversion efficiency of this new class of solar cells has been increased to a point where they are beginning to compete with more established technologies. Although PSCs have evolved a variety of structures, the use of hole-transporting materials (HTMs) remains indispensable. Here, an overview of the various types of available HTMs is presented. This includes organic and inorganic HTMs and is presented alongside recent progress in associated aspects of PSCs, including device architectures and fabrication techniques to produce high-quality perovskite films. The structure, electrochemistry, and physical properties of a variety of HTMs are discussed, highlighting considerations for those designing new HTMs. Finally, an outlook is presented to provide more concrete direction for the development and optimization of HTMs for highefficiency PSCs.

Growth and Exploration of Inorganic Semiconductor Electron and Hole Transport Layers for Low-Cost Perovskite Solar Cells

Trends in Sciences

The perovskite exhibited outstanding performance and was a promising alternative material for a low-cost, high power conversion efficiency (PCE) solar cell application. To avoid the high-cost organic materials as electron transport layers (ETL) and hole transport layers (HTL) in perovskite solar cells (PSCs), here introduce the inorganic semiconductor nanomaterials ZnS and CuS work as an ETL and HTL, respectively. In this work, we selected chalcogenides such as zinc sulfide (ZnS) and copper sulfide (CuS) as the 2-electron and hole transport layers and utilized them for perovskite solar cell application. For the proposed cell structure FTO/ZnS/perovskite (CH3NH3PbI3)/CuS/Ag, the deposition of layers has been achieved via different techniques such as thermal evaporation, spin coating and doctor blade, respectively. X-ray diffraction and Field effect scanning electron microscopy (FESEM) with Energy-dispersive X-ray spectroscopy were used to characterize the structural and morphological...

Polymer/Inorganic Hole Transport Layer for Low-Temperature-Processed Perovskite Solar Cells

Energies

In the search for improvements in perovskite solar cells (PSCs), several different aspects are currently being addressed, including an increase in the stability and a reduction in the hysteresis. Both are mainly achieved by improving the cell structure, employing new materials or novel cell arrangements. We introduce a hysteresis-free low-temperature planar PSC, composed of a poly(3-hexylthiophene) (P3HT)/CuSCN bilayer as a hole transport layer (HTL) and a mixed cation perovskite absorber. Proper adjustment of the precursor concentration and thickness of the HTL led to a homogeneous and dense HTL on the perovskite layer. This strategy not only eliminated the hysteresis of the photocurrent, but also permitted power conversion efficiencies exceeding 15.3%. The P3HT/CuSCN bilayer strategy markedly improved the life span and stability of the non-encapsulated PSCs under atmospheric conditions and accelerated thermal stress. The device retained more than 80% of its initial efficiency afte...

Recent Progress and Challenges of Electron Transport Layers in Organic–Inorganic Perovskite Solar Cells

Energies

Organic–inorganic perovskites are crystalline light absorbers which are gaining great attraction from the photovoltaic community. Surprisingly, the power conversion efficiencies of these perovskite solar cells have rapidly increased by over 25% in 2019, which is comparable to silicon solar cells. Despite the many advances in efficiency, there are still many areas to be improved to increase the efficiency and stability of commercialization. For commercialization and enhancement of applicability, the development of electron transport layer (ETL) and its interface for low temperature processes and efficient charge transfer are very important. In particular, understanding the ETL and its interface is of utmost importance, and when this understanding has been made enough, excellent research results have been published that can improve the efficiency and stability of the device. Here, we review the progress of perovskite solar cells. Especially we discuss recent important development of p...

Substantial improvement of perovskite solar cells stability by pinhole-free hole transport layer with doping engineering

Scientific reports, 2015

We fabricated perovskite solar cells using a triple-layer of n-type doped, intrinsic, and p-type doped 2,2',7,7'-tetrakis(N,N'-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) (n-i-p) as hole transport layer (HTL) by vacuum evaporation. The doping concentration for n-type doped spiro-OMeTAD was optimized to adjust the highest occupied molecular orbital of spiro-OMeTAD to match the valence band maximum of perovskite for efficient hole extraction while maintaining a high open circuit voltage. Time-dependent solar cell performance measurements revealed significantly improved air stability for perovskite solar cells with the n-i-p structured spiro-OMeTAD HTL showing sustained efficiencies even after 840 h of air exposure.

Impact of Organic Hole Transporting Material and Doping on the Electrical Response of Perovskite Solar Cells

The Journal of Physical Chemistry C, 2018

The hole transport material (HTM) layer is a key component of the perovskite solar cells (PSCs) that must be optimized to reach high efficiency. The development of new HTMs alternative to Spiro-OMeTAD and the understanding of the role of doping agents on these layers are important research axes in the field. It requires the use of appropriate characterization tools enabling to discriminate the bulk and interface effects. In the present paper, we fully analyze the effect of HTM doping and of the material on the impedance response of PSCs. The approach has been implemented on two different molecular HTMs, Spiro-OMeTAD and a new molecular carbazole HTM, called B186, and with various doping levels. We show that limitations by poor doping are characterized by an extra high frequency impedance loop which capacitance and resistance analysis gives the dielectric constant and conductivity of the material, respectively. On the other hand, the low frequency part of the spectra provides important information on the charge accumulation/outflow and on the recombination levels. More generally, the presented approach is of high practical interest for the development of new organic HTMs and for the optimization of the layer doping.

Molecular doping enabled scalable blading of efficient hole-transport-layer-free perovskite solar cells

Nature communications, 2018

The efficiencies of perovskite solar cells (PSCs) are now reaching such consistently high levels that scalable manufacturing at low cost is becoming critical. However, this remains challenging due to the expensive hole-transporting materials usually employed, and difficulties associated with the scalable deposition of other functional layers. By simplifying the device architecture, hole-transport-layer-free PSCs with improved photovoltaic performance are fabricated via a scalable doctor-blading process. Molecular doping of halide perovskite films improved the conductivity of the films and their electronic contact with the conductive substrate, resulting in a reduced series resistance. It facilitates the extraction of photoexcited holes from perovskite directly to the conductive substrate. The bladed hole-transport-layer-free PSCs showed a stabilized power conversion efficiency above 20.0%. This work represents a significant step towards the scalable, cost-effective manufacturing of ...