Periodic Reporting for period 1 - SiPerSol (Highly Efficient Yet Stable Triple Junction Silicon Heterojunction/Alloyed Sn-Pb Low Band Gap Perovskite/Halide Engineered I-Br High Band Gap Perovskite Tandem Solar Cell)
Période du rapport: 2021-08-01 au 2023-07-31
Final report of MSCA fellow-SiPerSol
1. Explanation of the work carried out by the beneficiaries and Overview of the progress
• The main purpose of this project is fabricating high performance stable perovskite (PSC)/PSC/silicon heterojunction (SHJ) tandem solar cell with evaporation/solution method.
• Simulations were carried out to reach the optimized thicknesses of both top-cell and mid-cell in triple junction devices.
• Mid-cell and top-cell PSC devices are fabricated and efficiency of 21% and 20% is obtained, respectively, and device parameters are among the highest values achieved so far by hybrid method.
• Tandem devices based on SHJ/mid-cell and SHJ/top-cell are successfully prepared and the efficiencies of >24% and >27% are obtained, respectively.
• The results of the project were presented in five different conferences. A manuscript is prepared and will be submitted. The whole process of tandem fabrication was presented to both political and industry decision makers as well as students. The detailed fabrication process was also provided to other team members, one visiting PhD student from Luxemburg University, and one R&D scientist from IPVF, France.
1.1 Objectives
A. O1: Deposition of high quality FAPbI3-based perovskite by evaporation-spin coating method was the main purpose of this objective. Stabilizing the α-FAPbI3 phase was the main challenge of this objective.
B. O2: Deposition of high bandgap high efficiency CsFAPb(IBrCl)3 perovskite by evaporation-spin coating method was the aim of this objective. Decreasing the Voc-bandgap deficit and inhibiting phase segregation upon light illumination were challenging in this objective.
C. O3: Fabricating of highly efficient and stable SHJ/PSC/PSC triple junction tandem solar cells was the main target in this objective. Deposition of top cell on mid cell perovskite, finding proper interconnection without optical and electrical losses, and current matching of all three devices together to achieve very high efficiency was very challenging.
D. Training objectives
My core and advanced research skills was totally improved through training on various deposition and characterization methods. I also equipped with the knowledge of fabricating highly efficient tandem solar cells. For transferrable skills, I have great experience in working with other researchers from different backgrounds and fields. I also participated in a leadership training course from EPFL, which is also very useful for my career development. My professional network also greatly enhanced by participating in different conferences in the field and presenting the results in different countries along Europe.
1. Explanation of the work carried out by the beneficiaries and Overview of the progress
• The main purpose of this project is fabricating high performance stable perovskite (PSC)/PSC/silicon heterojunction (SHJ) tandem solar cell with evaporation/solution method.
• Simulations were carried out to reach the optimized thicknesses of both top-cell and mid-cell in triple junction devices.
• Mid-cell and top-cell PSC devices are fabricated and efficiency of 21% and 20% is obtained, respectively, and device parameters are among the highest values achieved so far by hybrid method.
• Tandem devices based on SHJ/mid-cell and SHJ/top-cell are successfully prepared and the efficiencies of >24% and >27% are obtained, respectively.
• The results of the project were presented in five different conferences. A manuscript is prepared and will be submitted. The whole process of tandem fabrication was presented to both political and industry decision makers as well as students. The detailed fabrication process was also provided to other team members, one visiting PhD student from Luxemburg University, and one R&D scientist from IPVF, France.
1.1 Objectives
A. O1: Deposition of high quality FAPbI3-based perovskite by evaporation-spin coating method was the main purpose of this objective. Stabilizing the α-FAPbI3 phase was the main challenge of this objective.
B. O2: Deposition of high bandgap high efficiency CsFAPb(IBrCl)3 perovskite by evaporation-spin coating method was the aim of this objective. Decreasing the Voc-bandgap deficit and inhibiting phase segregation upon light illumination were challenging in this objective.
C. O3: Fabricating of highly efficient and stable SHJ/PSC/PSC triple junction tandem solar cells was the main target in this objective. Deposition of top cell on mid cell perovskite, finding proper interconnection without optical and electrical losses, and current matching of all three devices together to achieve very high efficiency was very challenging.
D. Training objectives
My core and advanced research skills was totally improved through training on various deposition and characterization methods. I also equipped with the knowledge of fabricating highly efficient tandem solar cells. For transferrable skills, I have great experience in working with other researchers from different backgrounds and fields. I also participated in a leadership training course from EPFL, which is also very useful for my career development. My professional network also greatly enhanced by participating in different conferences in the field and presenting the results in different countries along Europe.
1.2 Explanation of the work carried per WP
1.2.1 WP1
The FAPbI3-based low bandgap (~1.54 eV) PSC by two-step evaporation and then spin coating of organohalide solution was successfully fabricated. Not only the performance of the devices improved by optimization of the process parameters, but also the Voc and FF of the devices are among the highest values in all FAPbI3-based perovskites (Fig. 1(d)). The crystalline structure of the films show that the film mainly consists of perovskite phase. Moreover, the preferential growth occurred towards (001) plane, reducing the (011) planes, which is crucial for improving the stability confirmed by TEM analysis (Fig. 1(a)). The morphology and surface roughness of the films show that the domain size of about 1 µm and surface roughness of about 67 nm are formed, which demonstrate the high quality of the samples and high light trapping ability of the surface (Fig. 1(c)). PL of the sample reveals around 1% PLQY, 1.16 eV QFLS, and 0.11 V non-radiative losses in the films, illustrating high quality of the films (Fig.1(b)). The devices exhibit efficiencies of >20% with Jsc of >23 mA/cm2, Voc of >1050 mV, FF of >84%, and MPPT stability of >20% (Fig. 1(e,f)).
1.2.2 Work package 2
The high bandgap perovskites with the composition of CsFAPb(IBrCl)3 were successfully prepared. The XRD pattern as well as TEM analyses show that the samples mainly consist of perovskite phase. The films are also highly oriented along (001) direction, which is beneficial for charge transport and recombination reduction (Fig. 2(a)). SEM micrograph of the film also demonstrate that the film has average domain size of 450 nm (Fig. 2(b)). The films also show high PLQY value of >1% demonstrating QFLS of around 1.23 eV and non-radiative losses of just 0.11 V, revealing high film quality with low recombination centers (Fig. 2 (c)). The efficiency of 19.14% is obtained. The values of FF for these devices reach to >85%, which is one the highest values for perovskite devices (Fig. 2(d)). The MPPT stability of the device is also very high as shown in inset Fig. 2(f).
1.2.3 Work package 3
Tandem devices based on low and high bandgap PSC on SHJ were successfully fabricated. The FAPbI3-based and CsFAPb(IBrCl)3 PSCs with bandgap of 1.5 and 1.8 eV, respectively, were considered for simulation of current matching. The optimum thicknesses for these two PSCs on top of SHJ for achieving current matching is 1100 and 300 nm, respectively (Fig. 3(a)). The simulated EQE for triple junction device also show 14 mA/cm2 for the highest current density in triple junction device, which with considering accumulated Voc of around 3.03 V, and FF of around 82%, simulated efficiency of 34.78% would be obtained (Fig. 3(b)). The SEM micrograph of the PSC/SHJ double junction tandem on textured SHJ bottom cell is also shown in Fig. 3(d). As can be seen, the perovskite layer is fully covered on the textured surface of the bottom cell. The efficiency of this tandem reaches to >24% with the Voc and FF values of 1.8 V and >83%, respectively (Fig. 3(e)). In terms of high bandgap PSC/SHJ tandem, the efficiency of >27% was obtained with Voc and FF of 1.83 V and 77%, respectively (not shown). The MPPT stability of the low bandgap perovskite/SHJ tandem device is also good as shown in the Fig. 3(h). In conclusion, the devices show great efficiency with both low and high bandgap perovskites. The simulation also reveals great potential of triple junction devices. The results of this project pave the way to realize high potential efficiency of the triple junction devices in real life.
1.2.1 WP1
The FAPbI3-based low bandgap (~1.54 eV) PSC by two-step evaporation and then spin coating of organohalide solution was successfully fabricated. Not only the performance of the devices improved by optimization of the process parameters, but also the Voc and FF of the devices are among the highest values in all FAPbI3-based perovskites (Fig. 1(d)). The crystalline structure of the films show that the film mainly consists of perovskite phase. Moreover, the preferential growth occurred towards (001) plane, reducing the (011) planes, which is crucial for improving the stability confirmed by TEM analysis (Fig. 1(a)). The morphology and surface roughness of the films show that the domain size of about 1 µm and surface roughness of about 67 nm are formed, which demonstrate the high quality of the samples and high light trapping ability of the surface (Fig. 1(c)). PL of the sample reveals around 1% PLQY, 1.16 eV QFLS, and 0.11 V non-radiative losses in the films, illustrating high quality of the films (Fig.1(b)). The devices exhibit efficiencies of >20% with Jsc of >23 mA/cm2, Voc of >1050 mV, FF of >84%, and MPPT stability of >20% (Fig. 1(e,f)).
1.2.2 Work package 2
The high bandgap perovskites with the composition of CsFAPb(IBrCl)3 were successfully prepared. The XRD pattern as well as TEM analyses show that the samples mainly consist of perovskite phase. The films are also highly oriented along (001) direction, which is beneficial for charge transport and recombination reduction (Fig. 2(a)). SEM micrograph of the film also demonstrate that the film has average domain size of 450 nm (Fig. 2(b)). The films also show high PLQY value of >1% demonstrating QFLS of around 1.23 eV and non-radiative losses of just 0.11 V, revealing high film quality with low recombination centers (Fig. 2 (c)). The efficiency of 19.14% is obtained. The values of FF for these devices reach to >85%, which is one the highest values for perovskite devices (Fig. 2(d)). The MPPT stability of the device is also very high as shown in inset Fig. 2(f).
1.2.3 Work package 3
Tandem devices based on low and high bandgap PSC on SHJ were successfully fabricated. The FAPbI3-based and CsFAPb(IBrCl)3 PSCs with bandgap of 1.5 and 1.8 eV, respectively, were considered for simulation of current matching. The optimum thicknesses for these two PSCs on top of SHJ for achieving current matching is 1100 and 300 nm, respectively (Fig. 3(a)). The simulated EQE for triple junction device also show 14 mA/cm2 for the highest current density in triple junction device, which with considering accumulated Voc of around 3.03 V, and FF of around 82%, simulated efficiency of 34.78% would be obtained (Fig. 3(b)). The SEM micrograph of the PSC/SHJ double junction tandem on textured SHJ bottom cell is also shown in Fig. 3(d). As can be seen, the perovskite layer is fully covered on the textured surface of the bottom cell. The efficiency of this tandem reaches to >24% with the Voc and FF values of 1.8 V and >83%, respectively (Fig. 3(e)). In terms of high bandgap PSC/SHJ tandem, the efficiency of >27% was obtained with Voc and FF of 1.83 V and 77%, respectively (not shown). The MPPT stability of the low bandgap perovskite/SHJ tandem device is also good as shown in the Fig. 3(h). In conclusion, the devices show great efficiency with both low and high bandgap perovskites. The simulation also reveals great potential of triple junction devices. The results of this project pave the way to realize high potential efficiency of the triple junction devices in real life.
1.3 Impact
1.3.1 Impact 1: Future career opportunities of the researcher
After gaining so many experiences not only in terms of know-how of fabricating and characterizing high performance tandem devices, but also in terms of soft skills like project management, communicating with others, and leadership abilities, I got so many offers from different academia and industries such as PVLAB, EPFL and Hanwha Qcells in the same field.
1.3.2 Impact 2: Disseminate the action results
The results of SiPerSol are presented in:
1- HOPV 2022 Valencia,
2- EUPVSEC 2022 Milan,
3- E-MRS 2023 Strasbourg,
4- HOPV 2023 London,
5- PSCO 2023, Oxford,
6- Two manuscripts are under preparation.
1.3.3 Impact 3: Communicate the action activities to different target audiences
1- Introducing the laboratory activity and device fabrication were provided to several visitors came from high schools, industry, or stakeholders.
2- Participating in open day Neuchatel campus of EPFL for public and describing the tandem device performance to families and children.
3- Posting the results and tandem solar cell news in social media like linked-in, and Instagram to raise the awareness towards renewable energies.
1.3.1 Impact 1: Future career opportunities of the researcher
After gaining so many experiences not only in terms of know-how of fabricating and characterizing high performance tandem devices, but also in terms of soft skills like project management, communicating with others, and leadership abilities, I got so many offers from different academia and industries such as PVLAB, EPFL and Hanwha Qcells in the same field.
1.3.2 Impact 2: Disseminate the action results
The results of SiPerSol are presented in:
1- HOPV 2022 Valencia,
2- EUPVSEC 2022 Milan,
3- E-MRS 2023 Strasbourg,
4- HOPV 2023 London,
5- PSCO 2023, Oxford,
6- Two manuscripts are under preparation.
1.3.3 Impact 3: Communicate the action activities to different target audiences
1- Introducing the laboratory activity and device fabrication were provided to several visitors came from high schools, industry, or stakeholders.
2- Participating in open day Neuchatel campus of EPFL for public and describing the tandem device performance to families and children.
3- Posting the results and tandem solar cell news in social media like linked-in, and Instagram to raise the awareness towards renewable energies.