Query: Efficient planar heterojunction perovskite solar cells by vapour deposition

Candidate papers:

abstract: Many different photovoltaic technologies are being developed for large scale solar energy conversion. The wafer based first generation photovoltaic devices have been followed by thin film solid semiconductor absorber layers sandwiched between two charge selective contacts and nanostructured (or mesostructured) solar cells that rely on a distributed heterojunction to generate charge and to transport positive and negative charges in spatially separated phases. Although many materials have been used in nanostructured devices, the goal of attaining high efficiency thin film solar cells in such a way has yet to be achieved. Organometal halide perovskites have recently emerged as a promising material for high efficiency nanostructured devices. Here we show that nanostructuring is not necessary to achieve high efficiencies with this material: a simple planar heterojunction solar cell incorporating vapour deposited perovskite as the absorbing layer can have solar to electrical power conversion efficiencies of over 15 per cent (as measured under simulated full sunlight) This demonstrates that perovskite absorbers can function at the highest efficiencies in simplified device architectures, without the need for complex nanostructures.
author_names: Mingzhen Liu

Michael B Johnston

Henry J Snaith
title: Efficient planar heterojunction perovskite solar cells by vapour deposition
venue: Nature
year: 2013

abstract: Hybrid organic inorganic solar photovoltaic (PV) cells capable of directly converting sunlight to electricity have attracted much attention in recent years. Despite evident technological advancements in the PV industry, the widespread commercialisation of solar cells is still being mired by their low conversion efficiencies and high cost per Watt. Perovskites are an emerging class of semiconductors providing a low cost alternative to silicon based photovoltaic cells, which currently dominate the market. This thesis develops a series of studies on "all solid state perovskite solar cells" fabricated via vapour deposition which is an industrially accessible technique, to achieve planar heterojunction architectures and efficient PV devices. Chapter 2 presents a general outlook on the operating principles of solar cells, delving deeper into the specific operational mechanism of perovskite solar cells. It also explores the usual methods employed in the fabrication of perovskite thin films. Chapter 3 describes the experimental procedures followed during the fabrication of the individual components constituting the device from the synthesis of the precursors to the construction of the functioning perovskite PV devices. Chapter 4 demonstrates pioneering work involving the dual source vapour deposition (DSVD) of planar heterojunction perovskite solar cells which generated remarkable power conversion efficiency values surpassing 15% These significant results pave the way for the mass production of perovskite PVs. To further expand the range of feasible vapour deposition techniques, a two layer sequential vapour deposition (SVD) technique is explored in Chapter 5. This chapter focusses on identifying the factors affecting the fundamental properties of the vapour deposited films. Findings provide an improved understanding of the effects of precursor compositions and annealing conditions on the films. Chapter 5 concludes with a comparison between SVD and DSVD fabricated films, highlighting the benefits of each vapour deposition technique. Furthermore, hysteretic effects are analysed in Chapter 6 for the perovskite PV devices fabricated based on different structural configurations. An interesting discovery involving the temporary functioning of compact layer free perovskite PV devices suggests the presence of a built in field responsible for the hysteresis of the cells. The observations made in this chapter yield a new understanding of the functionality of individual cell layers. Combining the advantages of the optimum vapour deposition technique established in Chapter 4 and Chapter 5, with the enhanced understanding of perovskite PV cell operational mechanism acquired from Chapter 6, an ongoing study on an "all perovskite" tandem solar cell is introduced in Chapter 7. This demonstration of the "all perovskite" tandem devices confirms the versatility of perovskites for a broader range of PV applications.
author_names: Mingzhen Liu
title: Planar heterojunction perovskite solar cells via vapour deposition and solution processing
year: 2014

abstract: Recently, hybrid perovskite solar cells (PSCs) have attracted extensive attention due to their high efficiency and simple preparing process. Herein, a facile low pressure chemical vapor deposition (LPCVD) technology is first developed to fabricate PSCs, which can effectively reduce the over rapid intercalating reaction rate and easily overcome this blocking issue during the solution process. As a result, the prepared uniform perovskite films exhibit good crystallization, strong absorption, and long carrier diffusion length. More strikingly, CH3NH3PbI3 absorbers by LPCVD demonstrate excellent moisture resistant feature even under laser illumination and high temperature conditions, which indicates that our proprietary method is very suitable for the future low cost, nonvacuum production of the new generation photovoltaic devices. Finally, high efficiency of 12.73% is successfully achieved under fully open air conditions. To the best of our knowledge, this is the first report of efficient PSCs with such a high humidity above 60%
author_names: Paifeng Luo

Zhaofan Liu

Wei Xia

Chenchen Yuan

Ji-gui Cheng

Yingwei Lu
title: Uniform, stable, and efficient planar heterojunction perovskite solar cells by facile low pressure chemical vapor deposition under fully open air conditions.
venue: ACS applied materials interfaces
year: 2015

abstract: High performance planar heterojunction (PHJ) perovskite solar cells (PrSCs) with MAPbI3 perovskite films were fabricated using a facile, environmentally benign, efficient and low cost dip coating deposition approach on a bilayered ZnO/TiO2 electron transport system from aqueous non halide Pb(NO3)2. Outstanding performance of PrSCs was achieved due to the PHJ configuration of FTO/TiO2/ZnO/MAPbI3/spiro OMeTAD/MoO3/Ag. These PHJ PrSCs exhibited better performance and stability with thinner ZnO layers in contrast to those with mesoporous TiO2 scaffolds, indicating that the thickness of the ZnO layer in the PHJ architecture significantly affected the surface coverage, morphology, crystallinity, and stability of the MAPbI3 perovskite films processed by dip coating deposition.
author_names: Muhammad Adnan

Jae Kwan Lee
title: Highly efficient planar heterojunction perovskite solar cells with sequentially dip coated deposited perovskite layers from a non halide aqueous lead precursor
year: 2020

abstract: We report the use of ultra sonic spray coating under ambient conditions as a deposition technique for the fabrication of planar heterojunction CH3NH3PbI3 xClx perovskite solar cells. We make a first optimization of processing parameter space using this deposition technique, and explore the role of the temperature of the substrate during spray casting, the volatility of the casting solvent and the post deposition anneal on determining the efficiency of the resultant solar cells. We find that maximum device efficiency is correlated with the creation of dense films having a surface coverage above 85% When such films are incorporated into a solar cell device, power conversion efficiencies of up to 11% are realized. These results demonstrate that spray coating can be used in the large area, low cost manufacture of high efficiency solution processed perovskite solar cells.
author_names: Alexander T Barrows

Andrew J Pearson

Chankyu Kwak

Alan D F Dunbar

Alastair Buckley

David G Lidzey
title: Efficient planar heterojunction mixed halide perovskite solar cells deposited via spray deposition
year: 2014

abstract: Abstract Ultrathin and compact SnOx amorphous layers derived from SnCl4 were introduced at the interface of electron transport layer (ETL)/perovskite or FTO/ETL to enhance the electron coupling between layers, passivate the trapping defects and optimize the energy level alignment. As results of the increased interface electron collection and reduced interface recombination, the planer perovskite solar cell (PSC) with SnO2 nanocrystal (NC) ETL pre treated by SnCl4 (Cl SnO2) shows the power conversion efficiency (PCE) enhancement from 16.3% to 18.6% and the device hysteresis has also been significantly restrained. In comparison, the planer PSCs with traditional SnCl4 (SnO2 Cl) post treated SnO2 NC ETL makes the PCE increased from 16.3% to 17.3% These results indicate that both two kinds of treated ways could improve the performance of the PSCs but compared with the post treatment process, the devices based on Cl SnO2 pre treated ETL present superior performance, which is attributed to the closer contact and enhanced electron coupling between FTO and SnO2 NC ETL with Cl SnO2 in between.
author_names: Danli Zhang

Hanmin Tian

Shixiao Bu

Tingting Yan

Jinfeng Ge

Tao Lei

Wengang Bi

Like Huang

Ziyi Ge
title: Efficient planar heterojunction perovskite solar cells with enhanced FTO/SnO2 interface electronic coupling
year: 2020

abstract: Introduction of Cs into FAPbI3 displayed great potential to stabilize the black perovskite phase by forming FA1 xCs xPbI3, which has been investigated widely based on solution process. During solution processing, the over rapid intercalating reaction rate between PbI2 and A cations (FA+ and Cs+ can bring some undesirable structural transitions. However, in vapor assisted solution process (VASP) the over rapid intercalating reaction rate can be reduced effectively. In addition, the formation process can be regulated significantly by the intermediate perovskite phase. In this study, FACl was employed together with FAI to improve the FA0.9Cs0.1PbI3 films by VASP. In the vapor deposition process, the FACl and FAI vapor coreacted with the PbI2 solid films, preferentially forming the intermediate perovskite phase FA0.9Cs0.1PbI xCl y. The intermediate perovskite phase FA0.9Cs0.1PbI xCl y supplied a plenty of seeds for rapid nucleation of perovskite, which prolonged the crystallization time of FA0.9Cs0.1PbI3, and thus, a smooth FA0.9Cs0.1PbI3 film with suppressed nonradiative recombination, prolonged carrier lifetime and decreased trap state density was acquired. Corresponding planar heterojunction perovskite solar cells achieved a champion power conversion efficiency (PCE) of 16.39% with a Voc of 0.99 V, Jsc of 22.87 mA/cm2, and fill factor of 74.82% under reverse scanning. Meanwhile, a hysteresis index of the FACl 10 device was decreased to 0.024 compared with 0.075 of the control device. Moreover, under the condition of nitrogen atmosphere, the normalized PCE of FACl 10 device diminished only 4.9% which was more stable comparing with 31.88% diminishing of the control device after 30 days.
author_names: Jing Chen

Jia Xu

Chenxu Zhao

Bing Zhang

Xiaolong Liu

Songyuan Dai

Jianxi Yao
title: Efficient Planar Heterojunction FA1 xCs xPbI3 Perovskite Solar Cells with Suppressed Carrier Recombination and Enhanced Open Circuit Voltage via Anion Exchange Process.
venue: ACS applied materials interfaces
year: 2019

abstract: The in situ thermal annealing doctor blading was developed to fabricate high quality perovskite CH3NH3PbI3 thin film and efficient planar heterojunction perovskite solar cells (PHJ PSCs) in ambient condition with humidity of ~45% The morphology of CH3NH3PbI3 thin film fabricated by in situ thermal annealing doctor blading varied from random nanowires to oriented domains as increasing the substrate temperature, and the domain size became larger and larger with increasing substrate temperature. The PHJ PSCs with a structure of ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Ag was fabricated based on in situ thermal annealing doctor bladed CH3NH3PbI3 thin film in ambient condition, resulting in the power conversion efficiency up to 11.29% without obvious hysteresis under different scanning directions and speeds. The performance is comparable to that of PHJ PSCs fabricated by spin coating deposition in glovebox with the same structure. The research results suggested that efficient PHJ PSCs could be fabricated by large scale in situ thermal annealing doctor blading in ambient condition, which is matchable with large scale, roll to roll process and shows potential application in industrial production.
author_names: Han Wu

Chujun Zhang

Kongxian Ding

Lijuan Wang

Yongli Gao

Junliang Yang
title: Efficient planar heterojunction perovskite solar cells fabricated by in situ thermal annealing doctor blading in ambient condition
year: 2017

abstract: Abstract Obtaining high quality organic inorganic halide perovskite films that have smooth and continuous surfaces and large crystal domains and possess photoelectrical properties preferable for photovoltaic applications is of paramount importance to achieve high performance perovskite solar cells (PSCs) The introduction of other halide ions into the synthesis process of methylammonium lead triiodide, CH 3 NH 3 PbI 3 to fabricate CH 3 NH 3 PbI 3 x X x (X=Cl or Br) x 0) has been confirmed as an effective approach to optimize optoelectronic properties, thereby enhancing solar cell performance. However, the reported approaches to incorporate chlorine or bromine in perovskite films mainly take place during a liquid phase synthesis process. Here, we report on bromide regulated CH 3 NH 3 PbI 3 film formation through a low pressure vapor assisted deposition process. PbBr 2 was used to either replace or to be mixed with PbI 2 to form pre deposited films that were then reacted with CH 3 NH 3 I vapor. Detailed structural, spectroscopic, and morphological characterizations of the perovskite films unambiguously demonstrate the formation of CH 3 NH 3 PbI 3 films. However, bromine incorporation slows down the perovskite formation process through formation of an intermediate phase, CH 3 NH 3 PbBr x I y which improves the grain domains in the as fabricated perovskite films. Enhancements in power conversion efficiency (PCE) for the as fabricated planar heterojunction structured PSCs were found for samples in which bromine was incorporated. Meanwhile, transient photovoltage decay measurements revealed that carrier recombination was suppressed throughout the entire device. When mixed PbI 2 /PbBr 2 films with a molar ratio of 1:4 were used as re deposited films, an optimized PCE of 17.40% was obtained.
author_names: Jia Xu

Jian-nan Yin

Li Xiao

Bing Zhang

Jianxi Yao

Songyuan Dai
title: Bromide regulated film formation of CH3NH3PbI3 in low pressure vapor assisted deposition for efficient planar heterojunction perovskite solar cells
year: 2016

abstract: Abstract TiO2 is a best choice of electron transport layers in perovskite solar cells, due to its high electron mobility and stability. However, traditional TiO2 processing method requires rather high annealing temperature >500 degC) preventing it from application to flexible devices. Here, we show that TiO2 thin films can be synthesized via chemical bath deposition below 100 degC. Typically, a compact layer of rutile TiO2 is deposited onto fluorine doped tin oxide (FTO) coated substrates, in an aqueous TiCl4 solution at 70 degC. Through the optimization of precursor concentration and ultraviolet ozone surface modification, over 12% power conversion efficiency can be achieved for CH3NH3PbI3 based perovskite solar cells. These findings offer a potential low temperature technical solution in using TiO2 thin film as an effective transport layer for flexible perovskite solar cells.
author_names: Chao Liang

Wu Zhenhua

Pengwei Li

Jiajie Fan

Z Yiqiang

Guosheng Shao
title: Chemical bath deposited rutile TiO2 compact layer toward efficient planar heterojunction perovskite solar cells
year: 2017