Source: Solar Energy Materials and Solar Cells, Volume 206
Author(s): Jakapan Chantana, Kanta Tai, Haruki Hayashi, Takahito Nishimura, Yu Kawano, Takashi Minemoto
Abstract
Na-doped Cu2SnS3 (CTS) solar cells are fabricated and their carrier recombination is examined. The CTS absorbers on Mo-coated soda-lime glass substrates are grown by the sulfurization of NaF/Cu–SnS2 (900 nm) precursors. The NaF thickness is varied from 0 to 100 nm to vary the Na content in the resulting CTS absorbers. It is disclosed that the large grain with the uniformity of the material distribution (Cu, Sn, and S) in the Na-doped CTS absorber is obtained. With optimal Na doping (NaF thickness of 60 nm), the open-circuit voltage deficit (VOC,def) is obviously reduced, whereas short-circuit current density deficit (JSC,def) is not varied much. The reduction of VOC,def is attributable to the decrease in the carrier recombination across the device. The conversion efficiency (η) is consequently increased to approximately 4.7%. However, with severe Na doping (NaF thickness of over 75 nm), the VOC,def is clearly increased owing to the increase in the carrier recombination, thereby reducing the η. This is occurs because the Sn2S3 and Na2S secondary phases near the surface of the CTS film are formed with the severe Na doping. To further increase the η, the JSC,def is reduced through the decrease in CdS buffer thickness. Ultimately, the 5.1%-efficient CTS solar cell is obtained with the Na-doped CTS absorber prepared with the optimal NaF thickness of 60 nm.
by Sayantan Sasmal†‡, Shilendra Kumar Sharma‡, Soumyo Chatterjee?, Amlan J. Pal?, Shuvan Prashant Turaga#, Andrew Anthony Bettiol#, Raj Ganesh S. Pala*‡§, Sri Sivakumar*‡§?, and Suresh Valiyaveettil*†
Source: Solar Energy Materials and Solar Cells, Volume 205
Author(s): Fan Bu, Benlin He, Yang Ding, Xueke Li, Xuemiao Sun, Jialong Duan, Yuanyuan Zhao, Haiyan Chen, Qunwei Tang
Abstract
Carbon-based hole-transporting material (HTM)-free CsPbBr3 perovskite solar cells (PSCs) provide new opportunities for promoting the commercial application of PSCs because of the low cost, simple preparation process and excellent stability under various extreme conditions. One of the remaining problems for inorganic CsPbBr3 PSCs is the low power conversion efficiency (PCE) due to the large energy level difference and inefficient hole extraction at CsPbBr3/carbon interface. Herein, polyaniline/graphite (PANi/G) composites are incorporated into carbon electrode to tailor work function and to improve hole-selectivity of back electrode for enhanced energy level alignment and interfacial hole extraction, leading to a remarkably reduced energy loss and charge recombination. The HTM-free CsPbBr3 PSC based on carbon-PANi/G electrode achieves a PCE of 8.87%, which is increased by 43.8% in comparison with 6.17% for the control device. Moreover, the unencapsulated device shows excellent long-term moisture tolerance with the initial PCE maintaining 93.5% even exposure to air atmosphere with 80% RH at 25 °C over 50 days. The successful improvement of energy level alignment and charge extraction in device by directly incorporating PANi/G composites into carbon electrode offers a promising strategy in developing low-cost and efficient HTM-free PSCs.
Graphical abstract
By incorporating PANi/G composites into carbon electrode for enhanced energy level alignment and interfacial hole extraction, the unencapsulated HTM-free CsPbBr3 PSC achieves a champion power conversion efficiency of 8.87% and excellent operational stability.
In this report, a modeling approach is employed to study the effect of the grain boundaries (GBs) and their electronic activity on the performance parameters of the perovskite solar cells (PSCs). Our model is based on the 1- dimensional drift-diffusion framework to engage the electron (hole) defects formed in the GBs and the GB's location through the perovskite layer. Power conversion efficiency (PCE) of the PSC is optimized with regards to the perovskite layer thickness, GBs location and perovskite layer band offset with GBs layer. The results shows that the location or the distribution of the GBs can vary the PCE of PSCs from 12% to around 21%, thereby making proper morphology engineering and passivation of GBs is a chief requirement for achieving high efficiency. PCEs larger than 21% require GB defect densities below 1015cm−2. It is demonstrated that the band offset of about 100 meV with GB width of 1 nm could effectively suppress the negative impact of the GBs throughout the entire perovskite layer. Interestingly, GBs location at closer points to electron transport layer (ETL)/perovskite interface may give rise to higher PCEs, however, relatively stronger hysteresis in current values is observed. The results here provide insight into the effect of the GBs location and their corresponding type of defects on the hysteresis and the PSC performance and opens up new horizons to find solutions for current PSC's shortcomings.
Graphical abstract
We investigate the relevance of grain boundaries location and their electronic activity for optimizing the performance and minimizing the J-V Hysteresis in PSCs.
by Zhongli Wang,
Xianneng Song,
Yu Jiang,
Jidong Zhang,
Xi Yu,
Yunfeng Deng,
Yang Han,
Wenping Hu,
Yanhou Geng
A simple structure, nonchlorinated solvent processable donor–acceptor conjugated polymer based on a denser alkyl side chains strategy is obtained and exhibits reliable high hole mobility of up to 9.24 cm2 V−1 s−1 in organic thin film transistor (OTFT) using a bar coating technique, which has great potential for large‐scale material and device manufacturing of high mobility OTFTs.
Abstract
Herein, a simple structure, nonchlorinated solvent processable high mobility donor–acceptor conjugated polymer, poly(2,5‐bis(4‐hexyldodecyl)‐2,5‐dihydro‐3,6‐di‐2‐thienyl‐pyrrolo[3,4‐c]pyrrole‐1,4‐dione‐alt‐thiophene) (PDPPT3‐HDO), is reported. The enhanced solubility in nonchlorinated solvent is realized based on a denser alkyl side chains strategy by incorporating small size comonomer thiophene. An associated benefit of thiophene comonomer is the remarkable structural simplicity of the resulting polymer, which is advantageous for industrial scaling up. The alkyl side chain density and structure of PDPPT3‐HDO can efficiently control the self‐assembly properties in solution and film. By bar coating from o‐xylene solution, PDPPT3‐HDO forms aligned films and exhibits high hole mobility of up to 9.24 cm2 V−1 s−1 in organic thin film transistors (OTFTs). Notably, the bar‐coated OTFT based on PDPPT3‐HDO shows a close to ideal transistor model and a high mobility reliability factor of 87%. The multiple benefits of increased side chain density strategy may encourage the design of high mobility polymers that meet the requirements of mass production of OTFT materials and devices.
by Azat F. Akbulatov†, Sergey A. Tsarev‡, Moneim Elshobaki‡§, Sergey Yu. Luchkin‡, Ivan S. Zhidkov?, Ernst Z. Kurmaev??, Sergey M. Aldoshin†, Keith J. Stevenson‡, and Pavel A. Troshin*†‡
The nature of precursor solutions not only impacts the nucleation rate and crystallization kinetics of perovskite crystals, but also influences the physical properties of perovskite thin films. This Review presents the comprehensive understanding on the nature of perovskite precursor solutions and the formation mechanism of perovskite thin films from these precursor solutions.
Abstract
The composition, crystallinity, morphology, and trap‐state density of halide perovskite thin films critically depend on the nature of the precursor solution. A fundamental understanding of the liquid‐to‐solid transformation mechanism is thus essential to the fabrication of high‐quality thin films of halide perovskite crystals for applications such as high‐performance photovoltaics and is the topic of this Review. The roles of additives on the evolution of coordination complex species in the precursor solutions and the resulting effect on perovskite crystallization are presented. The influence of colloid characteristics, DMF/DMSO‐free solutions and the degradation of precursor solutions on the formation of perovskite crystals are also discussed. Finally, the general formation mechanism of perovskite thin films from precursor solutions is summarized and some questions for further research are provided.
by Shuang Yu,
Yajie Yan,
Mohamed Abdellah,
Tõnu Pullerits,
Kaibo Zheng,
Ziqi Liang
Nonconfinement structure is disclosed in 2D Dion–Jacobson perovskite (p‐xylylenediamine, PDMA)MAn−1PbnI3n+1 (n > 3), which promotes interlayer exciton splitting and charge transport, leading to an impressive power conversion efficiency (PCE) up to 11% in inverted planar solar cells with greatly enhanced stability.
Abstract
Dion–Jacobson (DJ) type 2D perovskites with a single organic cation layer exhibit a narrower distance between two adjacent inorganic layers compared to the corresponding Ruddlesden–Popper perovskites, which facilitates interlayer charge transport. However, the internal crystal structures in 2D DJ perovskites remain elusive. Herein, in a p‐xylylenediamine (PDMA)‐based DJ perovskite bearing bifunctional NH3+ spacer, the compression from confinement structure (inorganic layer number, n = 1, 2) to nonconfinement structure (n > 3) with the decrease of PDMA molar ratio is unraveled. Remarkably, the nonconfined perovskite displays shorter spacing between 2D quantum wells, which results in a lower exciton binding energy and hence promotes exciton dissociation. The significantly diminishing quantum confinement promotes interlayer charge transport leading to a maximum photovoltaic efficiency of ≈11%. Additionally, the tighter interlayer packing arising from the squeezing of inorganic octahedra gives rise to enhanced ambient stability.
Source: Solar Energy Materials and Solar Cells, Volume 204
Author(s): N. Sangiorgi, A. Sangiorgi, A. Dessì, L. Zani, M. Calamante, G. Reginato, A. Mordini, A. Sanson
Abstract
Fiber-shaped Dye-Sensitized Solar Cells (DSSFs) represent one of the most interesting technologies aimed at the light harvesting and the production of electricity for wearable applications. In order to boost DSSFs commercialization, their production costs and environmental impact must be reduced. To this end, a suitable strategy could be to build thin film-based devices endowed with metal-free organic sensitizers, exploiting their higher molar extinction coefficients compared to typical ruthenium-containing organometallic dyes. In this work, three thiazolo[5,4-d]thiazole-based organic dyes, TTZ3, TTZ5 and TTZ7, capable of strongly absorb visible light, were used for the first time to manufacture titanium wire-based DSSFs. DSSFs based on a thin TiO2 layer (5 μm) sensitized with the three organic dyes were prepared and tested and the obtained results show that power conversion efficiencies for the organic dyes (0.80%) are higher than that obtained with the reference N719 dye (0.45%). An efficiency of 0.99% with short circuit current density equal to 3 mA/cm2 was achieved when the TTZ7-based DSSFs were tested in diffuse illumination condition, highlighting the supremacy of these dyes compared to the metal-organic reference. The excellent photovoltaic performances of TTZ dyes were attributed to their better light harvesting properties, resulting in the production of higher photocurrent densities, which was confirmed by the electrochemical impedance spectroscopy (EIS) analysis. The superiority of organic dyes on DSSFs performances compared to N719, shown for the first time in this work, support the real possibility to apply these molecules for the preparation of efficient light-harvesting devices based on thin film photoanodes.
by Kai Oliver Brinkmann*†?, Junjie He*†‡?, Felix Schubert†, Jessica Malerczyk†, Cedric Kreusel†, Frederic van gen Hassend§, Sebastian Weber§, Jun Song*‡, Junle Qu*‡, and Thomas Riedl*†
by Hui Chen,
Qiang Luo,
Tao Liu,
Jing Ren,
Shuang Li,
Meiqian Tai,
Hong Lin,
Hongcai He,
Jinshu Wang,
Ning Wang
Low‐cost n‐type goethite (FeOOH) quantum dots (QDs) are introduced into the perovskite light‐absorber layer to fabricate efficient and stable perovskite solar cells (PSCs). As a result, the PSCs with FeOOH QDs obtain a significant efficiency enhancement from 16.6% to 19.7%. Most strikingly, the long‐term stability of PSCs with FeOOH QDs is significantly enhanced.
Abstract
Minimization of defects and ion migration in organic–inorganic lead halide perovskite films is desirable for obtaining photovoltaic devices with high power conversion efficiency (PCE) and long‐term stability. However, achieving this target is still a challenge due to the lack of efficient multifunctional passivators. Herein, to address this issue, n‐type goethite (FeOOH) quantum dots (QDs) are introduced into the perovskite light‐absorption layer for achieving efficient and stable perovskite solar cells (PSCs). It is found that the iron, oxygen, and hydroxyl of FeOOH QDs can interact with iodine, lead, and methylamine, respectively. As a result, the crystallization kinetics process can be retarded, thereby resulting in high quality perovskite films with large grain size. Meanwhile, the trap states of perovskite can be effectively passivated via interaction with the under‐coordinated metal (Pb) cations, halide (I) anions on the perovskite crystal surface. Consequently, the PSCs with FeOOH QDs achieve a high efficiency close to 20% with negligible hysteresis. Most strikingly, the long‐term stability of PSCs is significantly enhanced. Furthermore, compared with the CH3NH3PbI3‐based device, a higher PCE of 21.0% is achieved for the device assembled with a Cs0.05FA0.81MA0.14PbBr0.45I2.55 perovskite layer.
by Yifan Wang,
Jie Li,
Tengfei Li,
Jiayu Wang,
Kuan Liu,
Qianqian Jiang,
Jianguo Tang,
Xiaowei Zhan
Black phosphorous quantum dots are used as interlayers to modify both electron and hole transport layers in organic solar cells. The power conversion efficiencies of the nonfullerene and fullerene‐based devices are enhanced.
Abstract
Black phosphorous quantum dots (BPQDs) possess ambipolar charge transport, high mobility, and a tunable direct bandgap. Here, liquid‐exfoliated BPQDs are used as interlayers to modify both the electron transport layer and hole transport layer in organic solar cells (OSCs). The incorporation of BPQDs is beneficial to the formation of a cascade band structure and electron/hole transfer and extraction. The power conversion efficiency of the BPQDs‐incorporated OSC based on PTB7‐Th:FOIC blend is enhanced from 11.8% to 13.1%. In addition, power conversion efficiency enhancement is also achieved for other nonfullerene and fullerene‐based devices, demonstrating the universality of this interlayer methodology.
by Xupeng Gao,
Xiangtong Zhang,
Wenxu Yin,
Hua Wang,
Yue Hu,
Qingbo Zhang,
Zhifeng Shi,
Vicki L. Colvin,
William W. Yu,
Yu Zhang
Ruddlesden–Popper 2D perovskites with a formula of (A′)2(A)n−1BnX3n+1 are excellent materials for the next generation of optoelectronic devices. Their properties can be tuned by selecting different organic amines, metal halides, and number of layers for light‐emitting diodes and solar cells.
Abstract
Ruddlesden–Popper perovskites with a formula of (A′)2(A)n−1BnX3n+1 have recently gained widespread interest as candidates for the next generation of optoelectronic devices. The variations of organic cation, metal halide, and the number of layers in the structure lead to the change of crystal structures and properties for different optoelectronic applications. Herein, the different synthetic methods for 2D perovskite crystals and thin films are summarized and compared. The optoelectronic properties and the charge transfer process in the devices are also delved, in particular, for light‐emitting diodes and solar cells.
