High‐Performance Polymer Tandem Solar Cells Employing a New n‐Type Conjugated Polymer as an Interconnecting Layer

Zhang, Kai; Gao, Ke; Xia, Ruoxi; Wu, Zhihong; Sun, Chen; Cao, Jiamin; Liu, Qian; Li, Weiqi; Liu, Shiyuan; Huang, Fei; Peng, Xiaobin; Ding, Liming; Yip, Hin‐Lap; Cao, Yong

doi:10.1002/adma.201506270

Cited by 157 publications

(106 citation statements)

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“…PEIE was spin-coated on top of PEDOT:PSS as the charge recombination layer and a PCE of 8.66% was attained in the corresponding tandem OSCs. [136] Due to the superior electron transport property of PF3N-2TNDI, the PCE of the tandem OSC remained above 9.65% even when the thickness of PF3N-2TNDI increased to 20 nm. [135] To laminate the ETL thickness limitation, Zhang et al used a conjugated polymer PF3N-2TNDI as the ETL material to fabricate ICLs, and achieved a PCE of 11.35% in the tandem device.…”

Section: Solution Processable Conjugated Polymers As Ail Materials Inmentioning

confidence: 95%

Solution‐Processable Conjugated Polymers as Anode Interfacial Layer Materials for Organic Solar Cells

Hou

2018

Advanced Energy Materials

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With appropriate charge transport layers, one can rationally engineer the driving force, which generally refers to the built-in electric field in devices, so that electrons and holes can be effectively extracted to their respective electrodes, and thereby maximize the efficiency of OSCs. [4] There are two main types of charge transport materials that are commonly used in OSCs: anode interfacial layer (AIL) materials for hole collection and electron transport layer (ETL) materials for electron collection. However, at present, the development of AIL materials is comparatively lagging, as compared to ETL materials. For ETL materials, many materials, such as low-work-function metal, [5] small-molecule organic compounds, [6] nonconjugated and conjugated polymers, [7] and transition metal oxides (TMO), [8] have been proven effective in improving the electron collection efficiency in OSCs. In sharp contrast, only a few materials, such as poly(3,4ethylenedioxythiophene): (styrenesulfonate) (PEDOT:PSS) [9] and MoO 3 , [10] have been extensively used as AILs in OSCs. Generally, the AIL serves two functions: 1) Improving the selectivity and efficiency of hole transport and collection. First, by using AILs, the work function (W F ) of the anode can be effectively enhanced, which helps to construct a built-in electric field in the device with the combination of a low-W F cathode. The built-in electric field provides the fundamental driving force that transfers holes to the anode, where the holes are subsequently collected (Figure 1a). [11] Second, with the modification of the AILs, the W F of the anode can be enhanced to be higher than the positive integer charge-transfer state (E ICT + ) of the donor, in which case the Fermi-level pinning to the E ICT + level occurs to reduce the hole collection barrier at the anode interface (Figure 1b). [12] Third, AILs should effectively block the electrons, reducing the charge recombination at the interface. [13] 2) Improving the physical contact between the anodes and the active layers. With the modification of AILs, the hydrophilic surface of anodes can be changed, which enhances the wettability and film quality of the active layers deposited on the anode surfaces. Moreover, the anode surface can be smoothed by an AIL to passivate surface defects and pinholes, which decreases the leakage current of the OSC devices. To efficiently realize the above functions, AIL materials should possess several characteristics, including a high W F value, exceptional optical transparency, excellent hole In recent years, solution-processed conjugated polymers have been extensively used as anode interfacial layer (AIL) materials in organic solar cells (OSCs) due to their excellent film-forming property and low-temperature processing advantages. In this review, the authors focus on the recent advances in conjugated polymers as AIL materials in OSCs. Several of the main classes of solution-processable conjugated polymers, including poly(3,4-ethylenedioxythiophene):(styrenesulfonate), polyaniline, polyt...

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Section: Solution Processable Conjugated Polymers As Ail Materials Inmentioning

confidence: 95%

Solution‐Processable Conjugated Polymers as Anode Interfacial Layer Materials for Organic Solar Cells

Hou

2018

Advanced Energy Materials

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“…[44] For the evaluation of the color rendering indices, the experimental transmission of each device is folded with the AM1.5 spectrum to obtain the perceived transmission under solar illumination. The optical parameters of n and k for different films were measured using a dual rotating-compensator Mueller matrix ellipsometer (ME-L ellipsometer, Wuhan Eoptics Technology Co., Wuhan, China), as described in detail in the reference.…”

Section: Film and Device Characterizationsmentioning

confidence: 99%

Synergic Interface and Optical Engineering for High‐Performance Semitransparent Polymer Solar Cells

Shi

Xia

Sun

et al. 2017

Advanced Energy Materials

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both the top and bottom electrodes. These semitransparent PSCs (ST-PSCs) could be used as power generating windows and aesthetic architectural glasses, which are considered as the most appealing photovoltaic product for building integrated photovoltaic applications. [12][13][14][15][16][17][18] However, unlike opaque PSCs, the overall performance of ST-PSCs depends not only on the PCE but also the average visible transmittance (AVT) and color rendering properties. [19] Therefore, the great challenge for ST-PSCs is to achieve high PCE yet with good AVT and color rendering properties.Optimization of both the PCE and AVT in ST-PSCs is inherently challenging as these two performance parameters are difficult to optimize at the same time. The ideal optical condition for ST-PSC can be reached when the light passes through the device is only absorbed by the active layer but not the other layers such as the transparent electrodes and the interlayers, which allows the maximal amount of light transmitted through the devices. The ideal electronic condition for ST-PSC fulfilled if all the photons absorbed by the light harvesting layer can be dissociated and collected to generate photocurrent with internal quantum efficiency equal to 100%. [20] However, in real cases, the optical and electronic properties of the ST-PSCs are strongly affected by the choice of interlayers and transparent electrodes. For example, the interlayer not only can act as a charge selective layer to improve charge extraction in PSCs but also can act as an optical spacer that alters the optical field distribution within the device. [21] Depending on the choice of the transparent conductive material used for constructing the transparent electrode, it can be categorized as nonreflective or semireflective one. The latter case, which can be fabricated using ultrathin metal films (UTMFs) with the reflectance and transmittance depending on the thickness of the metal films, is of particular interest as it provides better flexibility in tuning the optical property of ST-PSCs. [22,23] However, the deposition of high quality and smooth UTMF, which is a prerequisite for achieving high transparency and conductivity, as top transparent conducting electrode for ST-PSCs is not straight forward and the film quality is strongly depending of the choice of underneath charge transport layer and deposition conditions. [24][25][26] In previous reports, tailored charge transport layers, such as a C 60 surfactant as electron transport layer (ETL) and MoS 2 as hole transport layer, had been In this study the thickness of the PTB7-Th:PC 71 BM bulk heterojunction (BHJ) film and the PF3N-2TNDI electron transport layer (ETL) is systematically tuned to achieve polymer solar cells (PSCs) with optimized power conversion efficiency (PCE) of over 9% when an ultrathin BHJ of 50 nm is used. Optical modeling suggests that the high PCE is attributed to the optical spacer effect from the ETL, which not only maximizes the optical field within the BHJ film but also facilitates the formation of a...

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“…[14][15][16][17][18][19] (iii) The involvement of suitable anode or cathode interface materials to reduce the interfacial energy barriers and facilitate an efficient hole or electron extraction from the active layer have also been demonstrated as effective approaches to enhance the PCE. 20,21 From the device engineering side, (iv) the introduction of ternary structures in the active layer with two-donors/one-acceptor or two-acceptors/one-donor to enhance the absorption and increase the short-circuit current (J sc ), 8,[22][23][24][25][26] (v) the use of tandem structures including two or more subcells connected in series with complementary absorption bands to reduce the thermalization losses and increase the open-circuit voltages (V oc ) [27][28][29] and (vi) the optimization of the film morphology of the active layer adopting solvent vapor annealing, thermal annealing, mixed solvent and/or solvent additives have also been proved to be successful methods to achieve high performance OSCs. [30][31][32] Besides, from the perspective of materials, the involvement of a suitable third component either through low ratio physical doping into the mixture of active layer, or as a third monomer by chemical bonding to the new random terpolymers and then used as new polymer donors 33,34 or non-fullerene polymer acceptors [35][36][37] have also been employed as facile and reliable approaches to enhance the PCE.…”

Section: Introductionmentioning

confidence: 99%

Enhanced power conversion efficiency in iridium complex-based terpolymers for polymer solar cells

et al. 2018

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By introducing various low concentrations of Iridium complexes to the famous donor polymer of PTB7-Th backbone, new heavy metal containing terpolymers have been demonstrated. When blended with PC 71 BM, an obvious increase of power conversion efficiency (PCE) is obtained in 1 mol% Ir containing polymer for different photovoltaic devices either using Ca or PDIN as cathode interface layers. The impact of molecular weight on the photovoltaic performance has been particularly considered by using three batches of control polymer PTB7-Th to ensure a fair and more convincing comparison. At similar molecular weight conditions (M n : 60 kg mol −1 , M w : 100-110 kg mol), the 1 mol% Ir containing PTB7-ThIr1/PC 71 BM blends exhibits enhanced PCE to 9.19% compared with 7.92% of the control PTB7-Th. Through a combination of physical measurement, such as optoelectrical characterization, GIWAXS and pico-second time-resolved photoluminescence, the enhancement are contributed from comprehensive factors of higher hole mobility, less bimolecular recombination and more efficient slow process of charge separation. 3-9 To improve the PCEs of OSCs, numerous strategies have been employed through materials innovation and device engineering. (i) The first and most important is to design and synthesize new suitable donor-acceptor (D-A) type conjugated oligomers or alternating copolymers with high optical absorption, low bandgap, relatively lower highest occupied molecular orbital (HOMO) energy levels and high hole mobility in order to function as good electron donors in BHJ OSCs. Among many different materials categories, fluorinated-thieno [3,4-b] thiophene-based PTB7 and PTB7-Th and derivatives have proven to be excellent candidates.3,10-13 (ii) To overcome the shortcomings of fullerenes, such as weak absorption in the solar spectrum range, limited structural and energy level variability as well as device instability of the most widely used fullerene acceptors, the exploration of high performance new non-fullerene electron acceptors which comprise electron-deficient building blocks with low-lying HOMO and lowest unoccupied molecular orbital energy levels, strong absorption and high electron mobilities finds increasing attention in the field of OSCs.14-19 (iii) The involvement of suitable anode or cathode interface materials to reduce the interfacial energy barriers and facilitate an efficient hole or electron extraction from the active layer have also been

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High‐Performance Polymer Tandem Solar Cells Employing a New n‐Type Conjugated Polymer as an Interconnecting Layer

Abstract: PSS achieve a high power conversion efficiency (PCE) of 11.35%. Moreover, flexible tandem cells with PCE over 10% are also demonstrated.

Cited by 157 publications

References 48 publications

Solution‐Processable Conjugated Polymers as Anode Interfacial Layer Materials for Organic Solar Cells

Solution‐Processable Conjugated Polymers as Anode Interfacial Layer Materials for Organic Solar Cells

Synergic Interface and Optical Engineering for High‐Performance Semitransparent Polymer Solar Cells

Enhanced power conversion efficiency in iridium complex-based terpolymers for polymer solar cells

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