Article
Nanoscience & Nanotechnology
Hyesun Yoo, Jun Sung Jang, Seung Wook Shin, Jiwon Lee, JunHo Kim, Dong Myeong Kim, In Jae Lee, Byeong Hoon Lee, Jongsung Park, Jin Hyeok Kim
Summary: This study reveals the correlation between the reaction pathway and the point defects in the CZTSe film, showing that different reaction pathways lead to different device performances and defect energy levels. Additionally, the growth rates of different binary selenides during the annealing process have a significant impact on the formation of point defects.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Energy & Fuels
Alex Jimenez-Arguijo, Ivan Cano, Fabien Atlan, Yuancai Gong, Kunal J. Tiwari, Marcel Placidi, Joaquim Puigdollers, Zacharie Jehl Li-Kao, Edgardo Saucedo, Sergio Giraldo
Summary: This study explores the effects of applied voltage on the CdS/kesterite interface quality during thermal post-deposition treatments above the critical temperature, and models the effects of a shallow doping density gradient on the current-voltage curves and external quantum efficiency. The results suggest that this defect engineering approach shows promise in improving charge carrier selectivity in kesterite devices.
Article
Chemistry, Physical
Xinsheng Liu, Songfeng Chang, Jingling Liu, Yajun Qiao, Erguang Jia, Xingfeng Shen, Shuang Li, Ke Cheng, Zuliang Du
Summary: The incorporation of Sb into CZTSe absorbers through a Sb2Se3 and Se co-selenization process significantly improves the quality of CZTSe absorber layers and boosts the efficiency of the solar cells. By tuning the Sb/(Cu + Zn + Sn) ratio to 6.67, the CZTSe solar cell shows the best device performance with an efficiency up to 9.64%.
JOURNAL OF POWER SOURCES
(2021)
Article
Energy & Fuels
David Nowak, Fabien Atlan, Devendra Pareek, Maxim Guc, Alejandro Perez-Rodriguez, Victor Izquierdo-Roca, Levent Guetay
Summary: This paper analyzes the influence of composition variations during the growth of CZTSe layers on defect concentrations and final absorber properties. The samples were prepared from sputtered metallic and alloyed Zn/Cu-Sn/(Sn)/Zn precursors, and the variation of sputtered Sn content facilitated different forms for the embedded Sn. The predominant formation reaction during annealing was tuned by the ratio of the alloys and the overall chemical composition in the precursor. The influence of different precursor compositions and corresponding reaction pathways on the resulting defects and optoelectronic properties were addressed.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Energy & Fuels
Muhammad Rehan, Ara Cho, Awet Mana Amare, Kihwan Kim, Jae Ho Yun, Jun-Sik Cho, Joo Hyung Park, Jihye Gwak, Donghyeop Shin
Summary: Sodium alkali doping is an effective way to improve the performance of CZTSe devices by passivating native defects. Various methods have been considered to incorporate sodium in CZTSe films, leading to a significant increase in sodium content regardless of the incorporation method.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Energy & Fuels
Fabien Atlan, Ignacio Becerril-Romero, Sergio Giraldo, Victoria Rotaru, Yudania Sanchez, Galina Gurieva, Susan Schorr, Ernest Arushanov, Alejandro Perez-Rodriguez, Victor Izquierdo-Roca, Maxim Guc
Summary: The thermal stability of Cu2ZnSnSe4 (CZTSe) absorber and CdS buffer layers in PV devices was investigated under soft post deposition treatments (PDTs) at around 200 degrees C. The results showed that the absorber degrades due to Cu/Zn disorder, negatively affecting device performance, while the buffer layer improves through the recrystallization of the CdS nanolayer, leading to enhanced efficiency. These findings highlight the low thermal stability of CZTSe/CdS-based PV devices under relatively low temperatures, which should be considered for the further development of kesterite PV technology.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Energy & Fuels
Sergio Giraldo, Robert Fonoll-Rubio, Zacharie Jehl Li-Kao, Yudania Sanchez, Lorenzo Calvo-Barrio, Victor Izquierdo-Roca, Alejandro Perez-Rodriguez, Edgardo Saucedo
Summary: Kesterite Cu2ZnSn(S,Se)(4) thin film technology is a promising low-cost solution in the field of photovoltaics, but efficiency improvement remains a challenge. This study introduces an innovative approach using ultrathin CuGa layers at the rear interface to enhance kesterite crystallinity and shows significant enhancement in photovoltaic performance.
PROGRESS IN PHOTOVOLTAICS
(2021)
Article
Chemistry, Multidisciplinary
Daniel Fritsch
Summary: In recent years, researchers have been searching for more efficient and environmentally friendly materials for the next generation of thin film solar cells. They have found that hybrid halide perovskites and chalcogenide materials crystallising in the kesterite structure show promising results. However, the naturally occurring Cu-Zn disorder in the kesterite crystal structure affects its properties. To understand this influence, first-principles calculations and hybrid functional calculations were performed. The results show that the Cu-Zn disorder leads to a slight increase in unit cell volume and a reduction in band gap, in agreement with experimental and theoretical findings.
APPLIED SCIENCES-BASEL
(2022)
Article
Energy & Fuels
Daniel Fritsch, Susan Schorr
Summary: Recent advances in exchange and correlation functionals in density functional theory calculations, together with powerful computing facilities, have made predictive computational materials science a reality. Climbing Jacob's ladder by using more accurate functionals improves result quality but also requires higher computational demands, particularly important for materials with incorrectly described electronic ground state properties.
JOURNAL OF PHYSICS-ENERGY
(2021)
Article
Chemistry, Physical
Wen He, Maxwell T. Wetherington, Kanchan Ajit Ulman, Jennifer L. Gray, Joshua A. Robinson, Su Ying Quek
Summary: Studies have shown that in the system of 2D polar metal-2D Ga covalently bonded to a SiC substrate, low-frequency Raman modes are mainly composed of out-of-phase shear modes in Ga and coupled to SiC phonons. The highest-frequency shear mode exhibits a significant blue-shift with increasing thickness.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Energy & Fuels
Uday Saha, Abhijit Biswas, Md Kawsar Alam
Summary: A novel solar cell structure was designed in this study, utilizing ACZTSe as the absorber layer and optimizing the thickness and carrier density of other layers to achieve higher efficiency than selenium rich CZTSe solar cells. The design also includes utilizing CZTSe as a back surface field layer and ITO as the back electrode.
Article
Nanoscience & Nanotechnology
Siyu Wang, Zhan Shen, Yue Liu, Yi Zhang
Summary: The quality of absorber layer in thin-film solar cells is crucial, and the stacking order of metal elements affects the growth mechanism and nanoscale morphology of the films. This study investigates the growth mechanism of kesterite-structured thin-film solar cells with two different stacking sequences. The results show that the location of Zn layers in the precursor films plays a significant role in the nanoscale morphology and growth mechanism of the CZTSe films. Solar cells fabricated with the selenized Mo/Zn/Cu/Sn/Cu films achieve the highest efficiency of 10.28%.
ACS APPLIED NANO MATERIALS
(2023)
Article
Chemistry, Physical
Kunal J. Tiwari, Robert Fonoll Rubio, Sergio Giraldo, Lorenzo Calvo-Barrio, Victor Izquierdo-Roca, Marcel Placidi, Yudania Sanchez, Alejandro Perez-Rodriguez, Edgardo Saucedo, Zacharie Jehl Li-Kao
Summary: The study presents a method to probe the depth morphology, defect profile, and possible secondary phases in thin film semiconductors. By analyzing the morphology of Kesterite films, it is found that more than 50% of the absorber is disconnected from the substrate, highlighting a potential limitation in Kesterite solar cells. Surface-sensitive techniques allow for accurate composition profiling and direct observation of defects in Kesterite.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Ilias Efthimiopoulos, Tim Kullmey, Sergio Speziale, Anna S. Pakhomova, Marcel Quennet, Beate Paulus, Anna Ritscher, Martin Lerch
Summary: The researchers investigated the high-pressure structural and vibrational behavior of the disordered kesterite-type Cu2ZnSnS4 compound at ambient temperature. They found a clear structural transition to a GeSb-type phase close to 15 GPa, along with a change in compressibility rate at about 8 GPa. Upon decompression, a disordered zinc blende/sphalerite structure is recovered.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2021)
Article
Physics, Multidisciplinary
Andrei Alexandru, Ivan Horvath
Summary: It has been proposed that there is a phase in thermal QCD at temperatures well above the chiral crossover, with elements of scale invariance in the infrared. The study focuses on the effective spatial dimensions of Dirac low-energy modes in this phase, revealing a different dimension structure compared to high energy modes, possibly originating from topology. This dimension structure may play a role in understanding the near-perfect fluidity of the quark-gluon medium observed in accelerator experiments.
PHYSICAL REVIEW LETTERS
(2021)
Article
Energy & Fuels
Max Hilaire Wolter, Romain Carron, Enrico Avancini, Benjamin Bissig, Thomas Paul Weiss, Shiro Nishiwaki, Thomas Feurer, Stephan Buecheler, Philip Jackson, Wolfram Witte, Susanne Siebentritt
Summary: Band tails have a significant impact on the power conversion efficiency of solar cells, particularly in relation to the open-circuit voltage loss. By incorporating alkali atoms, band tails can be deliberately adjusted to improve efficiency in thin-film solar cells. The presence of band tails increases radiative recombination and nonradiative recombination losses in solar cells.
PROGRESS IN PHOTOVOLTAICS
(2022)
Article
Nanoscience & Nanotechnology
Mohit Sood, Jakob Bombsch, Alberto Lomuscio, Sudhanshu Shukla, Claudia Hartmann, Johannes Frisch, Wolfgang Bremsteller, Shigenori Ueda, Regan G. Wilks, Marcus Baer, Susanne Siebentritt
Summary: In devices based on Zn(O,S)/CuInS2, interface recombination is mainly caused by defects near the interface rather than unfavorable energy-level alignment or Fermi-level pinning. Research has shown that the dominant recombination channel is present at the Zn(O,S)/CuInS2 interface.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Energy & Fuels
Mohit Sood, Aleksander Urbaniak, Christian Kameni Boumenou, Thomas Paul Weiss, Hossam Elanzeery, Finn Babbe, Florian Werner, Michele Melchiorre, Susanne Siebentritt
Summary: The study reveals the distinct interface recombination characteristics in copper indium di-selenide solar cells, which are not affected by reduced interface bandgap or Fermi-level pinning. Experimental analysis and numerical simulations suggest that the V-OC deficit may be related to acceptor defects, highlighting the need for complementary techniques to identify the cause of interface recombination in the devices.
PROGRESS IN PHOTOVOLTAICS
(2022)
Article
Energy & Fuels
Alex J. Lopez-Garcia, Oriol Blazquez, Cristobal Voz, Joaquim Puigdollers, Victor Izquierdo-Roca, Alejandro Perez-Rodriguez
Summary: This study reports the fabrication of UV-blue selective transparent solar cells based on ultrathin intrinsic hydrogenated amorphous silicon films, showing their potential for applications in building-integrated PV and agrophotovoltaics, as well as in low-power devices and Internet of Things devices as a cost-effective power source. The devices exhibit high visible transmittance, power conversion efficiency, and light utilization efficiency, demonstrating the potential of the proposed device architectures for the development of highly transparent devices.
Article
Nanoscience & Nanotechnology
Jonathan Rommelfangen, Sven Reichardt, Van Ben Chu, Ludger Wirtz, Phillip J. Dale, Alex Redinger
Summary: This study investigates the impact of strain and temperature on the growth mode of mono- and few-layer MoS2 grown on Muscovite mica. The results show that the determination of the number of MoS2 layers based solely on Raman spectroscopy is misleading due to strain and changes in growth mode. By combining atomic force microscopy, Raman spectroscopy, and ab initio calculations, it is revealed that the growth at 500 degrees C exhibits strained layer-by-layer growth up to three mono-layers, while at 700 degrees C, a strain release occurs and layer-by-layer growth is confined to the first mono-layer.
Article
Nanoscience & Nanotechnology
Omar Ramirez, Evandro Martin Lanzoni, Ricardo G. Poeira, Thomas P. Weiss, Renaud Leturcq, Alex Redinger, Susanne Siebentritt
Summary: Doping in chalcopyrite Cu(In,Ga)Se-2 is determined by intrinsic point defects. N-type and P-type conductivities can be achieved in CuInSe2 depending on growth conditions, while CuGaSe2 always behaves as a P-type semiconductor. The N-to-P transition in Cu-poor Cu(In,Ga)Se-2 occurs when the gallium content reaches the critical concentration of 15%-19%.
Article
Chemistry, Multidisciplinary
Ajay Singh, Jeremy Hieulle, Joana Ferreira Machado, Sevan Gharabeiki, Weiwei Zuo, Muhammad Uzair Farooq, Himanshu Phirke, Michael Saliba, Alex Redinger
Summary: This study reports on the coevaporation of CH3NH3I and SnI2 to obtain Sn [4+]-free absorbers, with Sn being only in the preferred oxidation state [+2]. The resulting films show excellent optoelectronic properties and good stability, indicating high potential in developing lead-free, high efficiency, and stable photovoltaic solar cells.
Review
Physics, Multidisciplinary
S. Siebentritt, T. P. Weiss
Summary: Chalcopyrite solar cells play a crucial role in mitigating the climate crisis due to their low carbon emissions. Improvements in efficiency have been achieved through post-deposition treatments with heavy alkalis. However, limitations in open circuit voltage are caused by tail states and band gap distribution. Increased diode factor hampers further efficiency improvements due to metastable defect transitions. Alloying with Ag shows potential for band-edge engineering and diode factor enhancement. Passivation of the back contact in state-of-the-art cells has been extensively researched. Tandem cells are expected to significantly improve efficiency. Chalcopyrite solar cells show promising potential as both bottom and top cells.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2023)
Article
Energy & Fuels
Alex J. Lopez-Garcia, Cristobal Voz, Jose Miguel Asensi, Joaquim Puigdollers, Victor Izquierdo-Roca, Alejandro Perez-Rodriguez
Summary: This study presents the fabrication of transparent solar cells using nanometric intrinsic hydrogenated amorphous silicon films and oxide thin films as transparent carrier selective contacts. These ultrathin devices exhibit photovoltaic effect, high visible transmittance, and shifted spectral response. The prototypes with 30 nm a-Si:H film achieved an average visible transmittance of 35% and a photovoltaic conversion efficiency of 2%, which is a record for oxide-based transparent solar cells. These findings highlight the potential of these architectures for highly transparent energy harvesters in various applications.
Article
Chemistry, Multidisciplinary
Christian Kameni Boumenou, Himanshu Phirke, Jonathan Rommelfangen, Jean-Nicolas Audinot, Shiro Nishiwaki, Tom Wirtz, Romain Carron, Alex Redinger
Summary: Alkali post deposition treatments (PDTs) have been used to improve the power conversion efficiency (PCE) of Cu(In,Ga)Se-2 solar cell devices. However, a detailed understanding of how PDTs impact the nanoscale optoelectronic properties is still lacking. In this study, various scanning probe techniques and spectroscopy methods were used to show that RbF PDT treatments result in an exchange of Rb with Cu at the surface. The existence of the RbInSe2 phase is unlikely to be responsible for the recent improvements in PCE.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Physics, Applied
Thomas Paul Weiss, Omar Ramirez, Stefan Paetel, Wolfram Witte, Jiro Nishinaga, Thomas Feurer, Susanne Siebentritt
Summary: Cu(In,Ga)Se2-based solar cells achieve power conversion efficiencies exceeding 23%. However, the fill factor of these cells is relatively low due to diode factors greater than 1, mainly caused by metastable defects in the Cu(In,Ga)Se2 alloy. Excitation-dependent photoluminescence measurements reveal that the increased diode factor can be well explained by the model of metastable defects. Optically measured diode factors impose a lower limit on the electrical diode factor of finished solar cells. Ag alloying provides a pathway to increase fill factors and efficiencies for Cu(In,Ga)Se2-based solar cells.
PHYSICAL REVIEW APPLIED
(2023)
Article
Energy & Fuels
Omar Ramirez, Jiro Nishinaga, Felix Dingwell, Taowen Wang, Aubin Prot, Max Hilaire Wolter, Vibha Ranjan, Susanne Siebentritt
Summary: The detrimental effect of tail states on V-OC in Cu(In,Ga)Se-2 solar cells has been shown. Alkali metals can reduce tail states by passivating charged defects at grain boundaries. This study investigates the effect of compositional variations and alkali incorporation on tail states in Cu(In,Ga)Se-2 films. The results reveal that sodium and potassium can decrease the density of tail states, even in the absence of grain boundaries, suggesting additional mechanisms beyond grain boundaries for the alkali effects. Moreover, doping-induced increase in sodium or potassium incorporation contributes to the reduced tail states, which are primarily caused by electrostatic potential fluctuations and influenced by grain interior properties. By analyzing the voltage loss in high-efficiency polycrystalline and single crystalline devices, this work presents a comprehensive model explaining the voltage loss in Cu(In,Ga)Se-2 based on the combined effect of doping on tail states and V-OC.
Article
Nanoscience & Nanotechnology
Aubin JC. M. Prot, Michele Melchiorre, Felix Dingwell, Anastasia Zelenina, Hossam Elanzeery, Alberto Lomuscio, Thomas Dalibor, Maxim Guc, Robert Fonoll-Rubio, Victor Izquierdo-Roca, Gunnar Kusch, Rachel A. Oliver, Susanne Siebentritt
Summary: The article discusses the achievement of record efficiency in chalcopyrite-based solar cells using a gallium gradient and reveals non-radiative recombination issues at the back contacts of industrial absorbers. The study proposes a model where discrete bandgap phases interlace to form an apparent gradient throughout the thickness of the absorber.
Article
Chemistry, Physical
Stener Lie, Maxim Guc, Venkatesh Tunuguntla, Victor Izquierdo-Roca, Susanne Siebentritt, Lydia Helena Wong
Summary: In this study, CXTS (X = Zn, Mn, Mg, Ni, Fe, Co, Ba, Sr) thin films are synthesized and their physical properties and device performance are compared, leading to the discovery of promising solar cell absorbers.
JOURNAL OF MATERIALS CHEMISTRY A
(2022)
