JIANG ZHI XUAN

The aprotic butyldimethylsulfonium‐driven MAPbI₃ perovskite shows a much more pronounced effect on the improvement of moisture stability compared to the protic butylammonium (BA)‐based counterpart. The BA having a potential hydrogen donor, which exists on the surface and/or grain boundaries, is vulnerable to H₂O‐induced degradation initiators, resulting in the faster hydration followed by the irreversible degradation of perovskites.

Abstract

Many organic cations in halide perovskites have been studied for their application in perovskite solar cells (PSCs). Most organic cations in PSCs are based on the protic nitrogen cores, which are susceptible to deprotonation. Here, a new candidate of fully alkylated sulfonium cation (butyldimethylsulfonium; BDMS) is designed and successfully assembled into PSCs with the aim of increasing humidity stability. The BDMS‐based perovskites retain the structural and optical features of pristine perovskite, which results in the comparable photovoltaic performance. However, the fully alkylated aprotic nature of BDMS shows a much more pronounced effect on the increase in humidity stability, which emphasizes a generic electronic difference between protic ammonium and aprotic sulfonium cation. The current results would pave a new way to explore cations for the development of promising PSCs.

A dopant‐free hole transporting material (HTM) named DMZ, is synthesized and applied in inverted planar perovskite solar cells (PSCs). High power conversion efficiency (PCE) (18.61%) and stable‐enhanced PSCs devices are achieved and after storage for nearly 560 h, 90% of the maximum PCE is retained in air with a relative humidity ≈ 45%–50% without any encapsulation.

Abstract

A new hole transporting material (HTM) named DMZ is synthesized and employed as a dopant‐free HTM in inverted planar perovskite solar cells (PSCs). Systematic studies demonstrate that the thickness of the hole transporting layer can effectively enhance the morphology and crystallinity of the perovskite layer, leading to low series resistance and less defects in the crystal. As a result, the champion power conversion efficiency (PCE) of 18.61% with J _SC = 22.62 mA cm⁻², V _OC = 1.02 V, and FF = 81.05% (an average one is 17.62%) is achieved with a thickness of ≈13 nm of DMZ (2 mg mL⁻¹) under standard global AM 1.5 illumination, which is ≈1.5 times higher than that of devices based on poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT:PSS). More importantly, the devices based on DMZ exhibit a much better stability (90% of maximum PCE retained after more than 556 h in air (relative humidity ≈ 45%–50%) without any encapsulation) than that of devices based on PEDOT:PSS (only 36% of initial PCE retained after 77 h in same conditions). Therefore, the cost‐effective and facile material named DMZ offers an appealing alternative to PEDOT:PSS or polytriarylamine for highly efficient and stable inverted planar PSCs.

A simple perovskite solar cell architecture, which is based on dopant‐free electron and hole conductors and carbon back contact deposited at room temperature, is demonstrated. The resulting architecture leads to the fabrication of cheap and highly efficient perovskite solar cells exhibiting unprecedented long‐term operational and UV stability thus hold immense potential for large‐scale deployment.

Abstract

Today's perovskite solar cells (PSCs) mostly use components, such as organic hole conductors or noble metal back contacts, that are very expensive or cause degradation of their photovoltaic performance. For future large‐scale deployment of PSCs, these components need to be replaced with cost‐effective and robust ones that maintain high efficiency while ascertaining long‐term operational stability. Here, a simple and low‐cost PSC architecture employing dopant‐free TiO₂ and CuSCN as the electron and hole conductor, respectively, is introduced while a graphitic carbon layer deposited at room temperature serves as the back electrical contact. The resulting PSCs show efficiencies exceeding 18% under standard AM 1.5 solar illumination and retain ≈95% of their initial efficiencies for >2000 h at the maximum power point under full‐sun illumination at 60 °C. In addition, the CuSCN/carbon‐based PSCs exhibit remarkable stability under ultraviolet irradiance for >1000 h while under similar conditions, the standard spiro‐MeOTAD/Au based devices degrade severely.

Publication date: Available online 4 December 2019

Source: Solar Energy Materials and Solar Cells

Author(s): Tianxing Xiang, Yulong Zhang, Han Wu, Jing Li, Long Yang, Kangwei Wang, Jianlong Xia, Zhao Deng, Junyan Xiao, Wei Li, Zhiliang Ku, Fuzhi Huang, Jie Zhong, Yong Peng, Yi-Bing Cheng

Graphical abstract

The defects in CsPbBr₃-based all-inorganic perovskite solar cells are dramatically reduced through a two-step sintering procedure, which simultaneously promotes the film densification and grain growth. As a result, the open-circuit voltage, fill factor and power conversion efficiency of thermally evaporated CsPbBr₃ perovskite solar cells are substantially enhanced.

Publication date: Available online 4 December 2019

Source: Solar Energy Materials and Solar Cells

Author(s): Ligang Xu, Yifan Li, Chi Zhang, Yan Liu, Chao Zheng, WenZhen Lv, Mingguang Li, Yonghua Chen, Wei Huang, Runfeng Chen

Graphical abstract

An effective approach to prepare cellulose as interface of organic solar cells (OSCs) with enhanced performance from rice straw of agroforestry residues is demonstrated. A highly efficient inverted OSC is constructed and a power conversion efficiency (PCE) of 12.01% is realized using PBDB‐T:IT‐M as the active layer, which shows over 9.4% improvement in the PCE compared to that of a counterpart device (PCE = 10.98%).

Abstract

Advanced interface materials made from petrochemical resources have been extensively investigated for organic solar cells (OSCs) over the past decades. These interface materials have demonstrated excellent performances in OSC devices. However, the limited resources, high‐cost, and non‐ecofriendly nature of petrochemical‐based interface materials restrict their commercial applications. Here, a facile and effective approach to prepare cellulose and its derivatives as a cathode interface layer for OSCs with enhanced performance from rice straw of agroforestry residues is demonstrated. By employing this carboxymethyl cellulose sodium (CMC) into OSCs, a highly efficient inverted OSC is constructed, and a power conversion efficiency (PCE) of 12.01% is realized using poly[(2,6‐(4,8‐bis(5‐(2‐ethyl‐hexyl)‐thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′] dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7‐bis(2‐ethylhexyl)benzo[1′,2′‐c: 4′,5′‐c′]dithiophene‐4,8‐dione): 3,9‐bis(2‐methylene‐((3‐(1, 1‐dicyanomethylene)‐6/7‐methyl)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d: 2′,3′‐d′]‐s‐indaceno[1,2‐b: 5, 6‐b′]dithiophene as the active layer, which shows over 9.4% improvement in PCE compared to that of a device without the CMC layer (PCE = 10.98%), especially the enhancement in short‐circuit current. The improved current densities and PCEs are attributed to the reduced work function, enhanced absorption, and improved interfacial contact by using CMC and ZnO as co‐interface. This approach of fabricating interface materials from biorenewable sources for OSCs is simple, scalable, and cost‐effective, representing a promising direction for the development of smart interface and green electronics.

Due to their fantastic properties, black phosphorous nanosheets (BPNSs) are an emerging 2D material bridging the gap between graphene and transition metal dichalcogenides. Chemical functionalization is an effective strategy in improving the ambient stability of BPNSs and to impart additional properties/functions. Herein, the latest developments of the chemical functionalization of BPNSs are summarized and the future directions are highlighted.

Abstract

Owing to their tunable direct bandgap, high charge carrier mobility, and unique in‐plane anisotropic structure, black phosphorus nanosheets (BPNSs) have emerged as one of the most important candidates among the 2D materials beyond graphene. However, the poor ambient stability of black phosphorus limits its practical application, due to the chemical degradation of phosphorus atoms to phosphorus oxides in the presence of oxygen and/or water. Chemical functionalization is demonstrated as an efficient approach to enhance the ambient stability of BPNSs. Herein, various covalent strategies including radical addition, nitrene addition, nucleophilic substitution, and metal coordination are summarized. In addition, efficient noncovalent functionalization methods such as van der Waals interactions, electrostatic interactions, and cation–π interactions are described in detail. Furthermore, the preparations, characterization, and diverse applications of functionalized BPNSs in various fields are recapped. The challenges faced and future directions for the chemical functionalization of BPNSs are also highlighted.

Due to their fantastic properties, black phosphorous nanosheets (BPNSs) are an emerging 2D material bridging the gap between graphene and transition metal dichalcogenides. Chemical functionalization is an effective strategy in improving the ambient stability of BPNSs and to impart additional properties/functions. Herein, the latest developments of the chemical functionalization of BPNSs are summarized and the future directions are highlighted.

Abstract

Owing to their tunable direct bandgap, high charge carrier mobility, and unique in‐plane anisotropic structure, black phosphorus nanosheets (BPNSs) have emerged as one of the most important candidates among the 2D materials beyond graphene. However, the poor ambient stability of black phosphorus limits its practical application, due to the chemical degradation of phosphorus atoms to phosphorus oxides in the presence of oxygen and/or water. Chemical functionalization is demonstrated as an efficient approach to enhance the ambient stability of BPNSs. Herein, various covalent strategies including radical addition, nitrene addition, nucleophilic substitution, and metal coordination are summarized. In addition, efficient noncovalent functionalization methods such as van der Waals interactions, electrostatic interactions, and cation–π interactions are described in detail. Furthermore, the preparations, characterization, and diverse applications of functionalized BPNSs in various fields are recapped. The challenges faced and future directions for the chemical functionalization of BPNSs are also highlighted.

Structure steering of MS _x /TiO₂ heterojunctions in photodegradation, water splitting, and CO₂ conversion are reviewed herein, mainly focusing on improved light harvesting, effective interfacial charge transfer, and affordable active sites for surface chemical reactions. Special focus is given to the quantum dot sensitized solar cells.

Abstract

Developing efficient and affordable catalysts is of great significance for energy and environmental sustainability. Heterostructure photocatalysts exhibit a better performance than either of the parent phases as it changes the band bending at the interfaces and provides a driving force for carrier separation, thus mitigating the effects of carrier recombination and back‐reaction. Herein, the photo/electrochemical applications of a variety of metal sulfides (MS _x ) (MoS₂, CdS, CuS, PbS, SnS₂, ZnS, Ag₂S, Bi₂S₃, and In₂S₃)/TiO₂ heterojunctions are summarized, including organic degradation, water splitting, and CO₂ reduction conversion. First, a general introduction on each MS _x material (especially bandgap structures) will be given. Then the photo/electrochemical applications based on MS _x /TiO₂ heterostructures are reviewed from the perspective of light harvesting ability, charge carrier separation and transportation, and surface chemical reactions. Special focus is given to CdS/TiO₂ and PbS/TiO₂‐based quantum dot sensitized solar cells. Ternary composites by taking advantages of positive synergetic effects are also well summarized. Finally, conclusions are made regarding approaches for structure design, and the authors' perspective on future architectural design and electrode construction is given. This work will make up the gap for TiO₂ nanocomposites and shed light on the fabrication of more efficient MS _x ‐metal oxide junctions in photo/electrochemical applications.

Publication date: Available online 29 November 2019

Source: Solar Energy Materials and Solar Cells

Author(s): Hamaneh Zarenezhad, Masoud Askari, Mohammad Halali, Navid Solati, Timucin Balkan, Sarp Kaya

An effective approach to prepare cellulose as interface of organic solar cells (OSCs) with enhanced performance from rice straw of agroforestry residues is demonstrated. A highly efficient inverted OSC is constructed and a power conversion efficiency (PCE) of 12.01% is realized using PBDB‐T:IT‐M as the active layer, which shows over 9.4% improvement in the PCE compared to that of a counterpart device (PCE = 10.98%).

Abstract

Advanced interface materials made from petrochemical resources have been extensively investigated for organic solar cells (OSCs) over the past decades. These interface materials have demonstrated excellent performances in OSC devices. However, the limited resources, high‐cost, and non‐ecofriendly nature of petrochemical‐based interface materials restrict their commercial applications. Here, a facile and effective approach to prepare cellulose and its derivatives as a cathode interface layer for OSCs with enhanced performance from rice straw of agroforestry residues is demonstrated. By employing this carboxymethyl cellulose sodium (CMC) into OSCs, a highly efficient inverted OSC is constructed, and a power conversion efficiency (PCE) of 12.01% is realized using poly[(2,6‐(4,8‐bis(5‐(2‐ethyl‐hexyl)‐thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′] dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7‐bis(2‐ethylhexyl)benzo[1′,2′‐c: 4′,5′‐c′]dithiophene‐4,8‐dione): 3,9‐bis(2‐methylene‐((3‐(1, 1‐dicyanomethylene)‐6/7‐methyl)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d: 2′,3′‐d′]‐s‐indaceno[1,2‐b: 5, 6‐b′]dithiophene as the active layer, which shows over 9.4% improvement in PCE compared to that of a device without the CMC layer (PCE = 10.98%), especially the enhancement in short‐circuit current. The improved current densities and PCEs are attributed to the reduced work function, enhanced absorption, and improved interfacial contact by using CMC and ZnO as co‐interface. This approach of fabricating interface materials from biorenewable sources for OSCs is simple, scalable, and cost‐effective, representing a promising direction for the development of smart interface and green electronics.

An effective approach to prepare cellulose as interface of organic solar cells (OSCs) with enhanced performance from rice straw of agroforestry residues is demonstrated. A highly efficient inverted OSC is constructed and a power conversion efficiency (PCE) of 12.01% is realized using PBDB‐T:IT‐M as the active layer, which shows over 9.4% improvement in the PCE compared to that of a counterpart device (PCE = 10.98%).

Abstract

Advanced interface materials made from petrochemical resources have been extensively investigated for organic solar cells (OSCs) over the past decades. These interface materials have demonstrated excellent performances in OSC devices. However, the limited resources, high‐cost, and non‐ecofriendly nature of petrochemical‐based interface materials restrict their commercial applications. Here, a facile and effective approach to prepare cellulose and its derivatives as a cathode interface layer for OSCs with enhanced performance from rice straw of agroforestry residues is demonstrated. By employing this carboxymethyl cellulose sodium (CMC) into OSCs, a highly efficient inverted OSC is constructed, and a power conversion efficiency (PCE) of 12.01% is realized using poly[(2,6‐(4,8‐bis(5‐(2‐ethyl‐hexyl)‐thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′] dithiophene))‐alt‐(5,5‐(1′,3′‐di‐2‐thienyl‐5′,7‐bis(2‐ethylhexyl)benzo[1′,2′‐c: 4′,5′‐c′]dithiophene‐4,8‐dione): 3,9‐bis(2‐methylene‐((3‐(1, 1‐dicyanomethylene)‐6/7‐methyl)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d: 2′,3′‐d′]‐s‐indaceno[1,2‐b: 5, 6‐b′]dithiophene as the active layer, which shows over 9.4% improvement in PCE compared to that of a device without the CMC layer (PCE = 10.98%), especially the enhancement in short‐circuit current. The improved current densities and PCEs are attributed to the reduced work function, enhanced absorption, and improved interfacial contact by using CMC and ZnO as co‐interface. This approach of fabricating interface materials from biorenewable sources for OSCs is simple, scalable, and cost‐effective, representing a promising direction for the development of smart interface and green electronics.

Publication date: February 2020

Source: Solar Energy Materials and Solar Cells, Volume 205

Author(s): Roja Singh, Sudeshna Ghosh, Anand S. Subbiah, Neha Mahuli, Shaibal K. Sarkar