Advanced

Role of annealing and photostability of organo-metal-halide semiconductors for solar cell applications

Sörell Jonsson, David LU (2016) KOO920 20151
Centre for Analysis and Synthesis
Abstract
Methyl ammonium lead halides (MAPbX3 , X=Cl-, Br-,I-), crystallizing in a perovskite structure, have in recent years been shown to be a promising material as a light harvesting material in solar cells. It has many interesting properties which makes it suitable for solar cell applications, such as near-optimal band gap and long electron-hole diffusion lengths, as well as the possibility of synthesizing the films from solution based methods. It is also possible to tune the band gap by making mixed compounds of MAPb(I1-xBrx)3 (0≤x≤1), which could make this compound suitable for tandem cell applications. In order to optimize these perovskites for tandem cells, there are many steps and properties that need investigation. In this work, band gap... (More)
Methyl ammonium lead halides (MAPbX3 , X=Cl-, Br-,I-), crystallizing in a perovskite structure, have in recent years been shown to be a promising material as a light harvesting material in solar cells. It has many interesting properties which makes it suitable for solar cell applications, such as near-optimal band gap and long electron-hole diffusion lengths, as well as the possibility of synthesizing the films from solution based methods. It is also possible to tune the band gap by making mixed compounds of MAPb(I1-xBrx)3 (0≤x≤1), which could make this compound suitable for tandem cell applications. In order to optimize these perovskites for tandem cells, there are many steps and properties that need investigation. In this work, band gap tuning and structural properties were investigated using both optical techniques such as UV-Vis and Photoluminescence, as well as X-Ray Diffraction. Furthermore, the effect of annealing was studied by making measurements before and after annealing. Also, theoretical calculations of tandem cells were done to find the optimal band gap for MAPb(I1-xBrx)3.
Bang gap tuning was achieved for MAPb(I1-xBrx)3 and the most efficient composition was calculated to MAPbI1.05Br1.95. Studies of annealing showed that the band gap onset becomes sharper after annealing. Peaks in XRD also became narrower, indicating either more homogenous samples or larger crystallite size.
When MAPb(I1-xBrx)3 is illuminated with light, a phase splitting occurs creating multiple band gaps. This may be a problem for tandem cells, since the optimal band gap is not stable. Due to the phase splitting, a 4-terminal solar cell may be the preferred choice since the efficiency calculations show that the efficiency is less prone to change as the band gap is varied. Developing stable MAPb(I1-xBrx)3 is necessary to produce efficient tandem solar cells. (Less)
Popular Abstract (Swedish)
Metylammonium-bly-halider (MAPbX3 , X=Cl-, Br-,I-), som kristalliserar i en perovskitstruktur, har de senaste åren visat sig vara ett lovande material för solceller. Det har många intressanta egenskaper som gör det passande för solceller, såsom ett optimalt bandgap och lång elektron/hål-diffusionslängd, samt möjligheten att tillverkas genom lösningsbaserade metoder. Det är också möjligt att justera bandgapet genom att tillverka föreningar med både brom och jod, MAPb(I1-xBrx)3 (0≤x≤1), vilket gör det här materialet passande för tandemsolceller. För att optimera dessa föreningar för tandemsolceller är det många egenskaper som behöver undersökas. I det här arbetet har bandgapet samt strukturella egenskaper undersökts med både optiska metoder... (More)
Metylammonium-bly-halider (MAPbX3 , X=Cl-, Br-,I-), som kristalliserar i en perovskitstruktur, har de senaste åren visat sig vara ett lovande material för solceller. Det har många intressanta egenskaper som gör det passande för solceller, såsom ett optimalt bandgap och lång elektron/hål-diffusionslängd, samt möjligheten att tillverkas genom lösningsbaserade metoder. Det är också möjligt att justera bandgapet genom att tillverka föreningar med både brom och jod, MAPb(I1-xBrx)3 (0≤x≤1), vilket gör det här materialet passande för tandemsolceller. För att optimera dessa föreningar för tandemsolceller är det många egenskaper som behöver undersökas. I det här arbetet har bandgapet samt strukturella egenskaper undersökts med både optiska metoder som UV-Vis och fotoluminiscens, samt röntgendiffraktion (XRD). Dessutom har uppvärmningssteget undersökts genom att utföra mätningar före och efter uppvärmning. Till sist har teoretiska beräkningar av tandemceller utförts för att hitta det optimala bandgapet för MAPb(I1-xBrx)3.
Justering av bandgapet för MAPb(I1-xBrx)3 utfördes och den mest effektiva sammansättningen beräknades till MAPbI1.05Br1.95. Studier av uppvärmningen visade att bandgapets ansats blir skarpare efter uppvärmning. Dessutom blev topparna i XRD smalare, vilket tyder på att proven antingen blivit mer homogena eller att kristallstorleken ökat.
När MAPb(I1-xBrx)3 belyses med ljus sker en fasseparation vilket skapar multipla bandgap. Denna egenskap är ett problem för tandemsolceller, eftersom att det optimala bandgapet inte tycks vara stabilt. På grund av fasseparationen är troligtvis en tandemcell med fyra terminal att föredra, eftersom att de teoretiska beräkningarna visar att verkningsgraden för en fyrterminal förändras mindre med bandgapet. Att utveckla stabila filmer av MAPb(I1-xBrx)3 är nödvändigt för att i framtiden kunna tillverka stabila tandemsolceller. (Less)
Please use this url to cite or link to this publication:
author
Sörell Jonsson, David LU
supervisor
organization
course
KOO920 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
materials chemistry, materialkemi
language
English
id
8570789
date added to LUP
2016-02-24 12:13:19
date last changed
2016-02-24 12:13:19
@misc{8570789,
  abstract     = {Methyl ammonium lead halides (MAPbX3 , X=Cl-, Br-,I-), crystallizing in a perovskite structure, have in recent years been shown to be a promising material as a light harvesting material in solar cells. It has many interesting properties which makes it suitable for solar cell applications, such as near-optimal band gap and long electron-hole diffusion lengths, as well as the possibility of synthesizing the films from solution based methods. It is also possible to tune the band gap by making mixed compounds of MAPb(I1-xBrx)3 (0≤x≤1), which could make this compound suitable for tandem cell applications. In order to optimize these perovskites for tandem cells, there are many steps and properties that need investigation. In this work, band gap tuning and structural properties were investigated using both optical techniques such as UV-Vis and Photoluminescence, as well as X-Ray Diffraction. Furthermore, the effect of annealing was studied by making measurements before and after annealing. Also, theoretical calculations of tandem cells were done to find the optimal band gap for MAPb(I1-xBrx)3. 
Bang gap tuning was achieved for MAPb(I1-xBrx)3 and the most efficient composition was calculated to MAPbI1.05Br1.95. Studies of annealing showed that the band gap onset becomes sharper after annealing. Peaks in XRD also became narrower, indicating either more homogenous samples or larger crystallite size. 
When MAPb(I1-xBrx)3 is illuminated with light, a phase splitting occurs creating multiple band gaps. This may be a problem for tandem cells, since the optimal band gap is not stable. Due to the phase splitting, a 4-terminal solar cell may be the preferred choice since the efficiency calculations show that the efficiency is less prone to change as the band gap is varied. Developing stable MAPb(I1-xBrx)3 is necessary to produce efficient tandem solar cells.},
  author       = {Sörell Jonsson, David},
  keyword      = {materials chemistry,materialkemi},
  language     = {eng},
  note         = {Student Paper},
  title        = {Role of annealing and photostability of organo-metal-halide semiconductors for solar cell applications},
  year         = {2016},
}