by Miao Zhang,
Zhuohan Zhang,
Jian Wang,
Qiaoshi An,
Hongshang Peng,
Weihua Tang,
Fujun Zhang
Ternary polymer solar cells (PSCs) are fabricated with PBDB‐T:PC71BM:INPIC‐Si as the active layers. The power conversion efficiency (PCE) reaches 13.26% for ternary PSCs with 20 wt% PC71BM, which is larger than that for INPIC‐Si or PC71BM‐based PSCs with PCEs of 11.79% or 6.26%. Light absorption, exciton distribution, and film morphology can be simultaneously optimized by incorporating appropriate PC71BM.
Ternary polymer solar cells (PSCs) are designed by incorporating varied PC71BM into a PBDB‐T:INPIC‐Si‐based binary system. The PC71BM incorporation can replenish weak absorption of PBDB‐T and INPIC‐Si in the short wavelength from 300 to 500 nm. Effective charge transport channels can be formed in ternary active layers due to good compatibility of the used materials. The optimized ternary PSCs exhibit a power conversion efficiency (PCE) of 13.26% with short‐circuit current density (JSC) of 20.98 mA cm−2, open‐circuit voltage of 0.892 V, and fill factor (FF) of 70.84%. The 13.26% PCE is among the top values for ternary PSCs with fullerene derivative and nonfullerene materials as acceptors. An approximately 12.5% PCE improvement is obtained compared with INPIC‐Si‐based binary PSCs, originating from simultaneously increased JSC and FF of the optimized ternary PSCs. The balanced photon harvesting is obtained in the whole wavelength range by regulating PC71BM content in acceptors, leading to increased JSC of ternary PSCs. The molecular arrangement and phase separation are well optimized in ternary blend films, resulting in the enhanced FF of ternary PSCs. The photogenerated exciton distribution is optimized according to optical field distribution of ternary active layers, which further support the JSC and FF improvement.
by Mokshin Suri†‡, Abhijit Hazarika†, Bryon W. Larson†, Qian Zhao†§, Marta Valle´s-Pelarda||†, Timothy D. Siegler‡, Michael K. Abney‡, Andrew J. Ferguson†, Brian A. Korgel*‡, and Joseph M. Luther*†
by Clayton J. Dahlman†#, Ryan A. DeCrescent‡#, Naveen R. Venkatesan†, Rhys M. Kennard†, Guang Wu+, Michael A. Everest§, Jon A. Schuller?, and Michael L. Chabinyc*†
The Shockley–Queisser model is a landmark in photovoltaic device analysis by defining an ideal situation as reference for actual solar cells. However, the model and its implications are easily misunderstood. Thus, we present a guide to help understand and to avoid misinterpreting it.
by Robin Kerremans,
Oskar J. Sandberg,
Simone Meroni,
Trystan Watson,
Ardalan Armin,
Paul Meredith
Carbon stack perovskite solar cells offer potential as a manufacturable architecture using techniques such as screen printing and are characterized by micron‐scale thick active junctions. Herein, an electro‐optical model is developed that explains the working mechanisms of charge generation and collection in these solar cells that not only provides deep insight but also can be used for device optimization.
Mesoporous carbon stack architecture is attracting considerable interest as a candidate for scalable, low‐cost perovskite solar cells amenable to high‐throughput manufacturing. These cells are characterized by microns‐thick mesoporous titania and zirconia layers capped by a nonselective carbon electrode with the whole stack being infused with a perovskite semiconductor. Although the architecture does not deliver the >20% power conversion efficiencies characteristic of perovskite planar and mesoporous geometries, it does produce cells with respectable efficiencies >16%, which is unexpected due to the carbon electrode being a nonideal anode and the active layers being so thick. Optimization of these cells requires an understanding of the coupled efficiencies of light absorption, charge generation, and extraction which is currently unavailable. Herein, a combined experimental‐simulation study that elucidates photogeneration and extraction is reported. By determining the optical constants of the individual components and using effective‐medium approximations, the internal quantum efficiencies (IQE) in both the titania and zirconia layers are determined to be ≈85%. Numerical drift‐diffusion simulations indicate that this high IQE is a consequence of the thick junctions reducing minority carrier concentrations at the electrodes, thereby decreasing surface recombination. This insight can now be used to tune the carbon stack for efficiency and simplicity.
The oxygen‐stabilizing effect of [6,6]‐phenyl‐11 C61‐butyric acid‐(3,4,5‐tris(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)phenyl)methanol ester (PCBB‐OEG) is investigated and it is found that the excellent electron transfer/extraction of PCBB‐OEG can reduce the generation of superoxides and enhance the stability of perovskite solar cells (pero‐SCs). The resulting pero‐0.1/[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM):PCBB‐OEG‐based pero‐SC delivers a high power conversion efficiency of 20.49% as well as high long‐term stability under ambient atmosphere at ≈50% humidity.
Poor stability is one of the main limiting factors for the commercialization of perovskite solar cells (pero‐SCs). The degradation of perovskite films is usually triggered by the reaction of the perovskite active layer with the superoxide when exposed in ambient atmosphere, which is not prevented by simple encapsulation. Herein, an oxygen‐stabilizing effect is found by utilizing a hydrophilic [6,6]‐phenyl‐C61‐butyric acid‐(3,4,5‐tris(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)phenyl)methanol ester (PCBB‐OEG) as a dopant of the perovskite film and electron‐transporting layer (ETL). PCBB‐OEG accelerates photoelectron transport in perovskite films and enhances the electron‐extracting ability of ETL. This process is demonstrated to efficiently prevent the reaction between electrons and oxygen to form a superoxide. Hence, the presence of PCBB‐OEG in the perovskite film improves its stability against oxygen. The stability and efficiency of pero‐SCs are further improved by doping PCBB‐OEG in [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) ETL. As a result, the p‐i‐n pero‐SCs with PCBB‐OEG as an additive in both the perovskite active layer and ETL show the best power conversion efficiency of 20.49%. Importantly, the related device retains 98% of this initial efficiency after 60 days of storage in ambient atmosphere without encapsulation.
by Chendi Gong,
Sichao Tong,
Keqing Huang,
Hengyue Li,
Han Huang,
Jian Zhang,
Junliang Yang
Flexible planar heterojunction perovskite solar cells are constructed with an architecture of polyethylene‐2,6‐naphthalate/indium tin oxide/SnO2/perovskite/spiro‐OMeTAD/Ag and fabricated via a combination of roll‐to‐roll microgravure printing and slot‐die coating under ambient conditions with a relative humidity of ≈40%, leading to a power conversion efficiency (PCE) up to 10.56% and an average PCE of 9.97%.
It is highly desirable to develop large‐scale, low‐cost fabrication processes for flexible perovskite solar cells (f‐PSCs) under ambient conditions for accelerating their potential commercialization. Roll‐to‐roll (R2R) printing technology enables high‐output manufacturing and is well suited for commercially processing f‐PSCs. Herein, triple‐cation f‐PSCs are developed with a planar heterojunction structure consisting of polyethylene‐2,6‐naphthalate/indium tin oxide/SnO2/perovskite/spiro‐OMeTAD/Ag via a combination of R2R microgravure printing and slot‐die coating under ambient conditions with a relative humidity of ≈40%. A mixture of isopropanol and water is used to dilute an as‐purchased SnO2 colloid solution and modify the contact between the electron‐transport layer (ETL) and substrate, leading to a smooth morphology of the R2R‐printed ETL SnO2 layer. Furthermore, suitable intrinsic organic salt additives and the N2 gas blowing‐assisted process are introduced to effectively improve the crystallization of the perovskite, resulting in a high‐quality perovskite film via R2R. After the optimization, the f‐PSCs based on the R2R‐printed ETL SnO2 and the perovskite film under an ambient condition show a power conversion efficiency (PCE) of up to 10.56% and an average PCE of 9.97%. This study provides a potential strategy for commercially fabricating f‐PSCs via a scalable and efficient R2R printing process.
by Yingping Fan,
Hongguang Meng,
Li Wang,
Shuping Pang
Perovskite solar cells are very promising for their high efficiency and solution‐process feasibility. Herein, some fabrication methods for gaining a high‐quality perovskite layer with long‐term stability are reviewed. These approaches significantly enhance the stability of perovskites, which makes it applicable for commercialization. However, these methods have some issues and it still leaves much room for further optimization.
Organic–inorganic hybrid perovskites (OIHPs) are one of the hottest fields on account of their immense potential for photovoltaics. As one of the most promising OIHPs, formamidinium (FA)‐based perovskites have been developed very fast in the past few years. The power conversion efficiency (PCE) has reached certified 24.2%, which is comparable with that of monocrystalline silicon solar cells. However, the easy formation of nonperovskite δ‐phase formamidinium lead triiodide (FAPbI3) at a low temperature needs to be solved when fabricating a high‐quality light absorber layer. Several strategies have been used to avoid the formation of δ‐phase FAPbI3 and improve phase stability in recent years such as tolerance factor adjustment, dimensional engineering, addictive processing, interfacial modification, defects passivation, and in situ growth. These approaches can enhance the phase stability to some extent; however, their contribution to long‐term stability and especially their real mechanism is still unknown. Herein, the relationships among the tolerance factors, the structure of FAPbI3, and the phase transition phenomenon are summarized. In addition, various methodologies and potential mechanisms for stabilizing α‐phase FAPbI3 at room temperature (RT) are discussed. In conclusion, a series of challenges in the popular processings of perovskite solar cells and their corresponding solutions that help achieve commercialization faster are summarized.
Diboron‐treated SnO2 exhibits some Sn3+ species, which serve as electron donors with more n‐type nature, resulting in the higher Fermi level on the surface of SnO2, promoting electron extraction and reducing carrier recombination in the electron transport layer (ETL)/perovskite interface. A power‐conversion efficiency of 22.04% is obtained in an n‐i‐p structure perovskite solar cell.
Energy‐level modulation between perovskite and carrier transport layers to obtain a promoted carrier extraction and reduced charge recombination is an effective way to achieve high‐efficiency perovskite solar cells. Here, diboron is used as an effective interfacial modifier between SnO2 and perovskite. By taking advantage of the higher Fermi level on the surface of SnO2 after diboron treatment, a power‐conversion efficiency of 22.04% in a solar cell device based on two‐step solution‐processed planar n‐i‐p structure is obtained. With the help of thorough characterizations, it is argued that the diboron‐treated SnO2 exhibits some Sn3+ species, which serve as electron donors with a more n‐type nature, promoting electron extraction and reducing carrier recombination in the electron transport layer (ETL)/perovskite interface. Further analysis speculates that the formation of surface diboron–oxygen Lewis pair induces a reducing state of diboron complexes, resulting in the spontaneous electron redistribution and the formation of Sn3+−O–• species. This provides an effective chemical approach to tune the energy alignment between the oxide ETL and absorber.
by Qiang Sun,
Hao Li,
Xiu Gong,
Huaxia Ban,
Yan Shen,
Mingkui Wang
An interconnected SnO2 thin film (composed of presynthesized SnO2 nanocrystals interconnected by amorphous phase SnOx) is proposed as an electron transport layer for efficient flexible perovskite solar cells. The interconnected SnO2 thin film enables fast electron extraction from the perovskite layer and retards nonradiative charge carrier recombination. Corresponding flexible solar cells demonstrate a power conversion efficiency as high as 16.29%.
This study reports on interconnected SnO2 electron transport layers (composed of presynthesized SnO2 nanocrystals interconnected by amorphous phase SnOx) processed at low temperature (120 °C) for highly efficient flexible perovskite solar cells. Herein, the amorphous phase SnOx serves as an effective binder to connect the SnO2 nanocrystals to obtain ultra‐smooth electron transport layers. Further characterization of the charge carrier kinetics at the perovskite/electron transport layer interface confirms that the interconnected SnO2 nanocrystals layer facilitates electron extraction and retards nonradiative charge carrier recombination. Consequently, a power conversion efficiency of 16.29% is achieved for flexible perovskite solar cells using the interconnected SnO2 electron transport layer on indium tin oxide/polyethylene terephthalate substrates.
by Ming-Yue Sui,
Zi-Rui Yang,
Yun Geng,
Guang-Yan Sun,
LiHong Hu,
Zhong-Min Su
The bistricyclic aromatic enes molecules with multiple conformations are selected to further explore the effect of conformation on performance systematically. Then, a machine learning model is used to screen the more matched donor and predict the energy conversion efficiency of the device. A route from microscopic conformation to macroscopic performance design and characterization for organic photovoltaic device is established.
Theoretical predictions of macroscopic performance (power conversion efficiencies [PCEs]) and experimental analyses for microscopic material (conformation) have always urged for organic photovoltaics. A series of acceptors based on multi‐conformation bistricyclic aromatic enes core have been designed. The results suggested that A4‐2, A5‐2, and T4‐2 show the full folded conformation, fitting, and exhibiting advantageous properties of various parts for acceptors effectively, thus getting high VOC and JSC (kCS/kCR exceeds 1012) as well. Their PCEs of devices matching different donors were predicted through machine learning (ML). In traditional device structures and crude environments, a maximum PCE is about seven times higher than original. Herein, a comprehensive investigation, ranging for conformations → donor/acceptor interfaces → morphology → PCEs, is carried out by pure theoretical methods. Therefore, this quantitative micro‐analysis combined with the ML intelligent prediction leads to a new approach in the development of the next generation of nonfullerene acceptors.
by Kai Wang*†?, Xiaoyang Liu‡?, Rong Huang‡, Congcong Wu†, Dong Yang†, Xiaowen Hu§, Xiaofang Jiang§, James C. Duchamp‡, Harry Dorn*‡, and Shashank Priya*†
by Antonio Agresti†‡¶, Sara Pescetelli†¶, Alessandro Lorenzo Palma†, Beatriz Marti´n-Garci´a§?, Leyla Najafi§, Sebastiano Bellani§, Iwan Moreels?, Mirko Prato?, Francesco Bonaccorso*§#, and Aldo Di Carlo*†‡
Chem. Commun., 2019, 55,9196-9199 DOI: 10.1039/C9CC04364K, Communication
Jiayuan Zhao, Rouhollah Tavakoli, Mohammad Mahdi Tavakoli Interface engineering by PFN-P2 and compositional engineering using water additive enable an efficient and stable perovskite solar cell with 20.5% efficiency. The content of this RSS Feed (c) The Royal Society of Chemistry
by Yang Wang,
Wei Chen,
Lei Wang,
Bao Tu,
Tian Chen,
Bin Liu,
Kun Yang,
Chang Woo Koh,
Xianhe Zhang,
Huiliang Sun,
Guocong Chen,
Xiyuan Feng,
Han Young Woo,
Aleksandra B. Djurišić,
Zhubing He,
Xugang Guo
Two novel donor–acceptor‐type hole‐transporting materials are developed and characterized. Due to the good energy level alignment, appropriate hole‐transporting ability, and most importantly, the excellent film morphology, the MPA‐BTTI‐based dopant‐free inverted perovskite solar cell exhibits a remarkable power conversion efficiency of 21.17% with negligible hysteresis and long‐time operational stability.
Abstract
Hole‐transporting materials (HTMs) play a critical role in realizing efficient and stable perovskite solar cells (PVSCs). Considering their capability of enabling PVSCs with good device reproducibility and long‐term stability, high‐performance dopant‐free small‐molecule HTMs (SM‐HTMs) are greatly desired. However, such dopant‐free SM‐HTMs are highly elusive, limiting the current record efficiencies of inverted PVSCs to around 19%. Here, two novel donor–acceptor‐type SM‐HTMs (MPA‐BTI and MPA‐BTTI) are devised, which synergistically integrate several design principles for high‐performance HTMs, and exhibit comparable optoelectronic properties but distinct molecular configuration and film properties. Consequently, the dopant‐free MPA‐BTTI‐based inverted PVSCs achieve a remarkable efficiency of 21.17% with negligible hysteresis and superior thermal stability and long‐term stability under illumination, which breaks the long‐time standing bottleneck in the development of dopant‐free SM‐HTMs for highly efficient inverted PVSCs. Such a breakthrough is attributed to the well‐aligned energy levels, appropriate hole mobility, and most importantly, the excellent film morphology of the MPA‐BTTI. The results underscore the effectiveness of the design tactics, providing a new avenue for developing high‐performance dopant‐free SM‐HTMs in PVSCs.
Ternary polymer solar cells are successfully developed by combining a fullerene derivative and a nonfullerene material as acceptors. The introduction of PC61BM into the PBDB‐TF:Y6 blend effectively improves the charge transport properties and reduces the nonradiative energy loss. Ultimately, the main photovoltaic parameters are simultaneously enhanced in the ternary devices, leading to an outstanding efficiency of 16.5% (certificated as 16.2%).
Abstract
Recent advances in the material design and synthesis of nonfullerene acceptors (NFAs) have revealed a new landscape for polymer solar cells (PSCs) and have boosted the power conversion efficiencies (PCEs) to over 15%. Further improvements of the photovoltaic performance are a significant challenge in NFA‐PSCs based on binary donor:acceptor blends. In this study, ternary PSCs are fabricated by incorporating a fullerene derivative, PC61BM, into a combination of a polymer donor (PBDB‐TF) and a fused‐ring NFA (Y6) and a very high PCE of 16.5% (certified as 16.2%) is recorded. Detailed studies suggest that the loading of PC61BM into the PBDB‐TF:Y6 blend can not only enhance the electron mobility but also can increase the electroluminescence quantum efficiency, leading to balanced charge transport and reduced nonradiative energy losses simultaneously. This work suggests that utilizing the complementary advantages of fullerene and NFAs is a promising way to finely tune the detailed photovoltaic parameters and further improve the PCEs of PSCs.
by Ki‐Won Seo,
Jaemin Lee,
Jihwan Jo,
Changsoon Cho,
Jung‐Yong Lee
A poly(3,4‐ethylenedioxythiophene)‐free and indium tin oxide (ITO)‐free junction‐free AgNN electrode with high optoelectrical properties is proposed for flexible organic solar cells (FOSCs). The electrical sheet resistance and optical transmittance can be controlled by both initial metal thickness and NN density; even a very thin Ag layer with appropriate NN density can show high transmittance and low sheet resistance, yielding a highly efficient FOSC.
Abstract
A novel approach to fabricate flexible organic solar cells is proposed without indium tin oxide (ITO) and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) using junction‐free metal nanonetworks (NNs) as transparent electrodes. The metal NNs are monolithically etched using nanoscale shadow masks, and they exhibit excellent optoelectronic performance. Furthermore, the optoelectrical properties of the NNs can be controlled by both the initial metal layer thickness and NN density. Hence, with an extremely thin silver layer, the appropriate density control of the networks can lead to high transmittance and low sheet resistance. Such NNs can be utilized for thin‐film devices without planarization by conductive materials such as PEDOT:PSS. A highly efficient flexible organic solar cell with a power conversion efficiency (PCE) of 10.6% and high device yield (93.8%) is fabricated on PEDOT‐free and ITO‐free transparent electrodes. Furthermore, the flexible solar cell retains 94.3% of the initial PCE even after 3000 bending stress tests (strain: 3.13%).
by Kai Wang,
Waqas Siddique Subhani,
Yulong Wang,
Xiaokun Zuo,
Hui Wang,
Lianjie Duan,
Shengzhong (Frank) Liu
The progress of research into metal cations for perovskite solar cells is discussed by focusing on the locations of the cations in perovskites, the modulation of the film quality, and the influence on the photovoltaic performance. Metal cations are considered in the order of alkali cations, alkaline earth cations, and then metal cations in the ds and d regions, and ultimately trivalent cations.
Abstract
Metal halide perovskite solar cells (PVSCs) have revolutionized photovoltaics since the first prototype in 2009, and up to now the highest efficiency has soared to 24.2%, which is on par with commercial thin film cells and not far from monocrystalline silicon solar cells. Optimizing device performance and improving stability have always been the research highlight of PVSCs. Metal cations are introduced into perovskites to further optimize the quality, and this strategy is showing a vigorous development trend. Here, the progress of research into metal cations for PVSCs is discussed by focusing on the position of the cations in perovskites, the modulation of the film quality, and the influence on the photovoltaic performance. Metal cations are considered in the order of alkali cations, alkaline earth cations, then metal cations in the ds and d regions, and ultimately trivalent cations (p‐ and f‐block metal cations) according to the periodic table of elements. Finally, this work is summarized and some relevant issues are discussed.
Author(s): Min Wang, Fengren Cao, Kaimo Deng, Liang Li
Abstract
Organic-inorganic perovskite solar cells have attracted extensive attentions due to the advantages such as high power conversion efficiency and easy fabrication over other counterparts. Mixed-cation perovskite is considered as one of the most efficient light absorbers for perovskite solar cells and the device performance has a close connection to the quality of the perovskite thin film. Herein, we systematically investigate the influence of adduct phase in the mixed-cation perovskite precursor film on the crystallization of the perovskite. By tuning the adduct phase through solvent engineering, we successfully optimize the morphology and optoelectronic properties of the perovskite film and the planar-type perovskite solar cells with a power conversion efficiency over 21% can be achieved. Our work provides an effective method to control the growth of the mixed-cation perovskite film and thus boost the device performance with enhanced efficiency and stability.
Graphical abstract
The manipulation of intermediate adduct phase in mixed-cation perovskite precursor through solvent engineering is demonstrated, which leads to the formation of high-quality perovskite films with an increased grain size and improved optoelectronic properties. An impressive power conversion efficiency of 21.2% is achieved for planar-type perovskite solar cells.
There is a requirement to develop more effective hole-transporting materials (HTMs) than commonly used 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) to fabricate highly efficient and stable perovskite solar cells. Herein, we reported a new HTM of N [2],N2,N [5],N5,N [11],N11-hexakis(4-methoxyphenyl)indolo[3,2,1-jk]carbazole-2,5,11-triamine (DCZ-OMeTAD) by employing indolo[3,2,1-jk]carbazole (DCZ) as a central building block. In addition, another DCZ-based HTM named as 4,4′,4''-(indolo[3,2,1-jk]carbazole-2,5,11-triyl)tris(N,N-bis(4-methoxyphenyl)aniline) (DCZ-OMeTPA) with different arylamines as the electron-rich branch was also synthesized for comparison. CH3NH3PbI3 and (NH2CHNH2PbI3)1-x(CH3NH3PbI3)x based perovskite solar cells (PSCs) by utilizing the low-cost DCZ-OMeTAD as HTM exhibited the power conversion efficiency (PCE) of 19.81% and 21.66%, respectively, which were significantly higher than those of Spiro-OMeTAD based devices (18.06% and 20.08%). Unfortunately, DCZ-OMeTPA based PSCs presented unsatisfied device performance compared with Spiro-OMeTAD based devices. We ascribe it to the inferior charge-extraction capability and poor hole mobility of DCZ-OMeTPA. What's more, DCZ-OMeTAD based device also delivered the best cell stability among three HTMs based PSCs, indicating that the newly designed concept by replacing spirobifluorene with DCZ has good potential for developing effective HTMs for high-performance PSCs.
A series of organic solar cells (OSCs) were prepared with J71 as donor and IT-4F, T6Me or T6Me:IT-4F as acceptor(s), respectively. The two binary OSCs exhibit the same open circuit voltage (VOC), complementary short circuit current density (JSC) and fill factor (FF). The same VOC of binary OSCs with J71 as donor indicate the similar lowest unoccupied molecular orbits (LUMO) levels of IT-4F and T6Me. Meanwhile, IT-4F and T6Me have complementary photon harvesting range, exhibiting great potential in preparing efficient ternary OSCs. The optimized ternary OSCs exhibit a 13.16% power conversion efficiency (PCE) with 50 wt% IT-4F in acceptors, resulting from the enhanced JSC and FF. The FFs of ternary OSCs can be gradually improved along with IT-4F content increase, indicating that the two acceptors may prefer to form an alloyed state. The alloyed state of two acceptors should be beneficial to Förster energy transfer from IT-4F to T6Me, providing another channel for improving exciton utilization efficiency. This work indicates that alloyed model should have great potential in preparing efficient ternary OSCs with large content of the third component by fully exerting the advantages of used materials.
Graphical abstract
Ternary organic solar cells with 13.16% efficiency by recombining the advantages of used materials and the corresponding binary OSCs.
Author(s): Na Han, Ting Ji, Wenyan Wang, Guohui Li, Zhanfeng Li, Yuying Hao, Yucheng Wu, Yanxia Cui
Abstract
Quasi two-dimensional (Quasi-2D) layered perovskites show higher stability with respect to three-dimensional (3D) perovskites. And compared with two-dimensional (2D) perovskites, quasi-2D perovskites exhibit an improvement in power conversion efficiency (PCE) of perovskite solar cells (PSCs) due to reduced exciton binding energy. So far, different strategies have been adopted to increase PCEs of the quasi-2D PSCs by forming high crystalline quasi-2D perovskite films. In this work, we show that the performance of the quasi-2D aromatic phenylethylammonium based PSCs can be improved greatly through interfacial engineering, i.e., by introducing a layer of SiO2 coated AuAg-alloyed nanoprisms (AuAgNPrisms@SiO2) before coating the active layer. As a result, the short circuit current density and PCE increased by 32.8% and 34.1%, respectively. Morphological studies show that the incorporated AuAgNPrisms@SiO2 particles can serve as inducers for forming highly smooth quasi-2D perovskite film. Comprehensive studies indicate that AuAgNPrisms@SiO2 can also reduce the series resistance, increase light absorption, induce the photon recycling scheme, and assist exciton dissociation at the interface. The combination of all these helpful effects contributes to the observed PCE improvement of quasi-2D PSCs. Our results provide novel insight into the effect of metallic nanoparticles on the quasi-2D perovskite film and on the performance of quasi-2D PSCs.
Interfacial engineering plays an important role on determining the charge extraction and recombination in organic solar cells (OSCs). In this paper, the performance of OSCs was improved by incorporating alkali metal salts into the ZnO electron transport layer (ETL). Under the optimal alkali salt concentration and film preparation condition, the power conversion efficiency of PTB7:PC71BM based device was enhanced from 7.581% to 9.074%, accounting for a 20% increase. Additionally, ZnO ETL doped with alkali metal salts can effectively improve light absorption, electron transport and extraction as well as the better interface contact between ETL and active layer, so as to achieve large short-circuit current density, fill factor, and small series resistance, respectively. This study provides a facile and low cost method to enhance efficiency of OSCs.
Graphical abstract
Alkali metal salts are incorporated into ZnO electron transporting layer to improve optical and electrical properties for organic solar cells.
