Query: Opportunities and challenges for tandem solar cells using metal halide perovskite semiconductors

Candidate papers:

abstract: Metal halide perovskite semiconductors possess excellent optoelectronic properties, allowing them to reach high solar cell performances. They have tunable bandgaps and can be rapidly and cheaply deposited from low cost precursors, making them ideal candidate materials for tandem solar cells, either by using perovskites as the wide bandgap top cell paired with low bandgap silicon or copper indium diselenide bottom cells or by using both wide and small bandgap perovskite semiconductors to make all perovskite tandem solar cells. This Review highlights the unique potential of perovskite tandem solar cells to reach solar to electricity conversion efficiencies far above those of single junction solar cells at low costs. We discuss the recent developments in perovskite based tandem fabrication, and detail directions for future research to take this technology beyond the proof of concept stage.Perovskites, with their wide bandgap range, are good partners for both commercial and novel photovoltaic technologies in multijunction solar cells. Here, McGehee and co workers review recent material and device developments and highlight future challenges and opportunities for perovskite based tandems.
author_names: T Leijtens

Kevin A Bush

Rohit Prasanna

Michael D McGehee
title: Opportunities and challenges for tandem solar cells using metal halide perovskite semiconductors
year: 2018

abstract: Summary Organic inorganic halide perovskites are promising semiconductors to mate with silicon in tandem photovoltaic cells due to their solution processability and tunable complementary bandgaps. Herein, we show that a combination of two additives, MACl and MAH2PO2, in the perovskite precursor can significantly improve the grain morphology of wide bandgap (1.64 1.70 eV) perovskite films, resulting in solar cells with increased photocurrent while reducing the open circuit voltage deficit to 0.49 0.51 V. The addition of MACl enlarges the grain size, while MAH2PO2 reduces non radiative recombination through passivation of the perovskite grain boundaries, with good synergy of functions from MACl and MAH2PO2. Matching the photocurrent between the two sub cells in a perovskite/silicon monolithic tandem solar cell by using a bandgap of 1.64 eV for the top cell results in a high tandem Voc of 1.80 V and improved power conversion efficiency of 25.4%
author_names: Bo Chen

Zhengshan J Yu

Kong Liu

Xiaopeng Zheng

Ye Liu

Jianwei Shi

Derrek Spronk

Peter N Rudd

Zachary C Holman

Jinsong Huang
title: Grain Engineering for Perovskite/Silicon Monolithic Tandem Solar Cells with Efficiency of 25.4%
year: 2019

abstract: Abstract Multi junction tandem design has been proven to be an effective means to further improve the efficiency of solar cells. However, its share in the photovoltaics market at present is tiny, since the most efficient tandem device comprises III V semiconductors, which entail the use of expensive fabrication processes. The advent of perovskite solar cells, which have revitalized the PV field with their unprecedented pace of development, promises to address this bottleneck. Perovskite materials could not only serve as the top subcell absorber for commercial solar cells including Si and copper indium gallium selenide, but could work efficiently as bottom subcells owing to highly tuneable bandgaps which extend down to the range of ~1.2 to 1.5 eV. The highest efficiency perovskite tandem to date was achieved by pairing a perovskite top cell with a Si bottom cell in a four terminal configuration, yielding 26.4% This review gives an overview of recent progress on the main tandem structures, and describes the detailed design improvements that have resulted in new record efficiencies. Ultimately, commercialization of these tandem solar cells relies on the scalability of perovskite technology. We, therefore, highlight the development of large scale tandems and approaches to produce perovskite modules. We also point out the critical aspects that will require further effort and provide guidelines for future developments. The potential obstacles that will hamper the commercialization of perovskite tandems, if not adequately addressed, namely device stability and toxicity, are then critically examined. Finally, the substantial opportunities that perovskite materials open up for other solar devices with a tandem configuration are mentioned, which are attracting increasing attention.
author_names: Heping Shen

The Duong

Yiliang Wu

Jun Peng

Daniel A Jacobs

Nandi Wu

Klaus J Weber

Thomas P White

Kylie R Catchpole
title: Metal halide perovskite: a game changer for photovoltaics and solar devices via a tandem design
year: 2018

abstract: The past decade has witnessed the growing interest in metal halide perovskites as driven by their promising applications in diverse fields. The low intrinsic stability of the early developed organic versions has however hampered their widespread applications. Very recently, all inorganic perovskite nanocrystals have emerged as a new class of materials that hold great promise for the practical applications in solar cells, photodetectors, light emitting diodes, and lasers, among others. In this Outlook, we first discuss the recent developments in the preparation, properties, and applications of all inorganic metal halide perovskite nanocrystals, with a particular focus on CsPbX3, and then provide our view of current challenges and future directions in this emerging area. Our goal is to introduce the current status of this type of new materials to researchers from different areas and motivate them to explore all the potentials.
author_names: Qiao Zhang

Yadong Yin
title: All Inorganic Metal Halide Perovskite Nanocrystals: Opportunities and Challenges
venue: ACS central science
year: 2018

abstract: Metal halide perovskites have recently emerged as promising photovoltaic materials for application in solar cells with high power conversion efficiencies exceeding 23 In the years since such high efficiencies have been attained, investigations have mainly focused on the state of the art 3 D Pb based halide perovskite materials. However, the high toxicity of Pb and intrinsic instability of the pristine perovskite materials have become great obstacles to their industrial application and commercialization. To address these serious issues, it is imperative to explore low toxicity metal halide perovskites or their derivatives to substitute Pb based materials for better future development. Currently, Bi based halide perovskite like materials are attracting increased interest as environmentally friendly alternatives for photovoltaic applications. This Concept highlights recent advances of Bi based halide perovskite like materials in terms of understanding and modifying their fundamental properties and related device performance, with a focus on current challenges, opportunities for future development, and diversification of device applications.
author_names: Long-Jiang Zhang

Kai Wang

Bo Zou
title: Bismuth Halide Perovskite Like Materials: Current Opportunities and Challenges.
venue: ChemSusChem
year: 2019

abstract: Metal halide perovskites have recently attracted enormous attention for photovoltaic applications due to their superior optical and electrical properties. Lead (Pb) halide perovskites stand out among this material series, with a power conversion efficiency (PCE) over 25% According to the Shockley Queisser (SQ) limit, lead halide perovskites typically exhibit bandgaps that are not within the optimal range for single junction solar cells. Partial or complete replacement of lead with tin (Sn) is gaining increasing research interest, due to the promise of further narrowing the bandgaps. This enables ideal solar utilization for single junction solar cells as well as the construction of all perovskite tandem solar cells. In addition, the usage of Sn provides a path to the fabrication of lead free or Pb reduced perovskite solar cells (PSCs) Recent progress in addressing the challenges of fabricating efficient Sn halide and mixed lead tin (Pb Sn) halide PSCs is summarized herein. Mixed Pb Sn halide perovskites hold promise not only for higher efficiency and more stable single junction solar cells but also for efficient all perovskite monolithic tandem solar cells.
author_names: Shuai Gu

Renxing Lin

Qiaolei Han

Yuan Gao

Hairen Tan

Jia Zhu
title: Tin and Mixed Lead Tin Halide Perovskite Solar Cells: Progress and their Application in Tandem Solar Cells.
venue: Advanced materials
year: 2020

abstract: Abstract In several photovoltaic (PV) technologies, the presence of electronic defects within the semiconductor band gap limit the efficiency, reproducibility, as well as lifetime. Metal halide perovskites (MHPs) have drawn great attention because of their excellent photovoltaic properties that can be achieved even without a very strict film growth control processing. Much has been done theoretically in describing the different point defects in MHPs. Herein, we discuss the experimental challenges in thoroughly characterizing the defects in MHPs such as, experimental assignment of the type of defects, defects densities, and the energy positions within the band gap induced by these defects. The second topic of this Review is passivation strategies. Based on a literature survey, the different types of defects that are important to consider and need to be minimized are examined. A complete fundamental understanding of defect nature in MHPs is needed to further improve their optoelectronic functionalities.
author_names: Luis K Ono

Shengzhong Frank Liu

Yabing Qi
title: Reducing Detrimental Defects for High Performance Metal Halide Perovskite Solar Cells
venue: Angewandte Chemie
year: 2019

abstract: The electronic and material properties of graphene have been explored in a number of electronic and optoelectronic devices including organic and metal halide perovskite solar cells have been explored. At present, graphene based technology is considered to have many potential applications. Moreover, graphene related materials offer graphene like characteristics and the tunability of chemical, electrical and physical properties through doping and functionalization. Metal halide perovskite solar cells form the most advanced photovoltaic technology, showing an exponential increase in their certified power conversion efficiency. The most pronounced challenge is the stability of these devices, which has limited their practical applications and commercialization. The synergy between the properties of metal halide perovskite semiconductors and GRMs has recently been revealed and has contributed towards the realization of highly efficient perovskite solar cells with impressive operational stability. In this work, we review the progress made in the specific field of graphene based metal halide perovskite solar cells since 2013. The impact of exploitation of graphene and GRMs on this photovoltaic technology is multi fold, since it has resulted in the development of high quality perovskite crystals for the fabrication of more stable and flexible devices exhibiting high performance.
author_names: Costantinos Petridis

George Kakavelakis

Emmanuel Kymakis
title: Renaissance of graphene related materials in photovoltaics due to the emergence of metal halide perovskite solar cells
year: 2018

abstract: DOI: 10.1002/aenm.201803135 For a two terminal monolithic tandem solar cell, the open circuit voltage (VOC) is the sum of the VOCs of the wide bandgap and low bandgap subcells while the shortcircuit current density (JSC) is limited by the lower JSC of the subcells. Therefore, achieving high VOCs for both subcells while maintaining a sufficiently high JSC for current matching is critical for realizing high efficiency two terminal tandem solar cells. For all perovskite tandem solar cells, the commonly used wide bandgap (wide Eg) subcell (1.7 1.9 eV) is based on FA1 xCsxPb(I1 yBry)3 perovskite absorbers (0 x, y 1) (FA formamidinium, Cs cesium, I iodide, Br bromide) whereas the low bandgap (low Eg) (1.1 1.3 eV) subcell is based on tin (Sn) lead (Pb) halide perovskite absorbers.[12 15] While wide Eg PSCs have achieved remarkable improvement in performance via composition tuning/engineering, annealing engineering, and interface engineering,[16 19] the performances of low Eg PSCs reported in the literature are still not satisfactory. Significant efforts have been made to improve the performance of low Eg PSCs.[6,11,20 27] Kanatzidis and coworkers have first reported the bowing effect in mixed Sn Pb perovskites, revealing the opportunity of bandgap tuning via compositional engineering.[20] McGehee and co workers have studied the effect of lattice contraction and octahedral tilting on bandgap tuning in low Eg mixed Sn Pb perovskites.[21] Hayase and co workers have introduced an n type "spike structure" interface to improve the charge flow at the interface of the absorber and electron transport layer (ETL)[28] Our group has boosted the efficiency to a certified value of 17% for relatively thick low Eg (1.25 eV) PSCs, beneficial for all perovskite tandem solar cells.[6,23,24,29] Recently, Jen and coworkers have incorporated 20% Br into low Eg MASn0.5Pb0.5I3 (MA methylammonium) perovskite to obtain an optimal bandgap (1.35 eV) for single junction PSC applications, and a VOC of 0.9 V was obtained.[26] However, the relatively large Eg limits its potential for applications as the low Eg bottom subcells for tandem devices.[13] So far, many reported lowEg mixed Sn Pb PSCs show relatively large VOC deficits (Eg/q VOC, where q is the unit charge) and/or low fill factors The unsatisfactory performance of low bandgap mixed tin (Sn) lead (Pb) halide perovskite subcells has been one of the major obstacles hindering the progress of the power conversion efficiencies (PCEs) of all perovskite tandem solar cells. By analyzing dark current density and distribution, it is identified that charge recombination at grain boundaries is a key factor limiting the performance of low bandgap mixed Sn Pb halide perovskite subcells. It is further found that bromine (Br) incorporation can effectively passivate grain boundaries and lower the dark current density by two three orders of magnitude. By optimizing the Br concentration, low bandgap (1.272 eV) mixed Sn Pb halide perovskite solar cells are fabricated with open circuit voltage deficits as low as 0.384 V and fill factors as high as 75% The bestperforming device demonstrates a PCE of >19% The results suggest an important direction for improving the performance of low bandgap mixed Sn Pb halide perovskite solar cells.
author_names: Chongwen Li

Zhaoning Song

Dewei Zhao

Chuanxiao Xiao

Biwas Subedi

Niraj Shrestha

Maxwell M Junda

Changlei Wang

Chunsheng Jiang

Mowafak M Al-Jassim

Randy J Ellingson

Nikolas J Podraza

Kai Zhu

Yanfa Yan
title: Reducing Saturation Current Density to Realize High Efficiency Low Bandgap Mixed Tin Lead Halide Perovskite Solar Cells
year: 2019

abstract: Today's photovoltaics market is dominated by single junction solar cells with a crystalline silicon (c Si) absorber. Higher efficiencies can be achieved in tandem junction devices, with a thin top cell converting the high energy part of the solar spectrum in a wide bandgap absorber, and a bottom c Si cell converting the low energy part of the spectrum [1] Alternatively, lower manufacturing costs can be achieved for polycrystalline solar cells based on direct bandgap absorbers such as Cu(In,Ga)Se2. In both cases, the research focus lies on the development of cost effective, high efficiency thin film (TF) solar cells with polycrystalline absorbers, including CdTe, Cu(In,Ga)Se2, III/V semiconductors and metal halide perovskites such as the archetypical methyl ammonium lead iodide (MAPI)
author_names: Michael E Stuckelberger

Tara Nietzold

Bradley M West

Trumann Walker

Christina Ossig

Maik Kahnt

Felix Wittwer

Jixia Deng

Jorg M Maser

B Lai

Zhonghou Cai

Volker Rose

Andrew Ulvestad

Martin V Holt

Stephan O Hruszkewycz

James J Dynes

Justin Wang

Damien Salomon

Remi Tucoulou

X Huang

H Yan

Evgeny Nazaretski

Yong S Chu

Christian G Schroer

Mariana I Bertoni
title: Challenges and Opportunities with Highly Brilliant X ray Sources for multi Modal in Situ and Operando Characterization of Solar Cells
venue: Microscopy and Microanalysis
year: 2018