Unravelling the working junction of aqueous-processed polymer–nanocrystal solar cells towards improved performance

Chen, Zhaolai; Du, Xiaohang; Jin, Gan; Zeng, Qingsen; Liu, Fangyuan; Yang, Bai

doi:10.1039/c6cp02600a

Cited by 16 publications

(18 citation statements)

References 43 publications

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“…On the contrary, a negative sign is produced due to electrons accumulating at the surface area nearby the top electrode . In our previous work, we discovered that there exists polymer‐rich domain on the surface of polymer/CdTe hybrid films . Therefore, holes will accumulate on the surface of hybrid films nearby the top electrode, thus leading to a positive signal.…”

Section: Resultsmentioning

confidence: 96%

“…As such high temperature (over 400 °C) will severely damage the electronic properties of polymers, the investigations of the influences of Cl content and grain size on photovoltaic performance are only based on inorganic CdTe NCs in this section. Figure a shows the J‐V curves of the photovoltaic devices based on CdTe NCs annealed at different temperature, and the detailed photovoltaic parameters extracted from J‐V curves for a batch of six devices are listed in Table .…”

Section: Resultsmentioning

confidence: 99%

“…This is mainly attributed to the more efficient exciton transfer processes and reduced light absorption of polymers, thus leading to decreasd geminate recombination . In the HSCs system with broad absorption range and high absorption coefficient acceptor and wide‐bandgap donor, NCs act as principal light absorber and carrier transporter, while polymers mainly play the roles of hole acceptor and interface dipole generator, which can increase carrier lifetime and V oc , respectively . Therefore, high‐quality NCs are vital to achieve high‐performance HSCs.…”

Section: Introductionmentioning

confidence: 99%

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Aqueous‐Processed Polymer/Nanocrystals Hybrid Solar Cells: The Effects of Chlorine on the Synthesis of CdTe Nanocrystals, Crystal Growth, Defect Passivation, Photocarrier Dynamics, and Device Performance

et al. 2017

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High‐quality nanocrystals (NCs) are vital to achieve high‐performance polymer/nanocrystals hybrid solar cells (HSCs). However, in‐depth investigation on aqueous CdTe NCs related properties is extraordinarily insufficient, thus, limiting the further improvement of the device performance of aqueous‐processed HSCs. In this work, the effects of chlorine (Cl) on the synthesis of aqueous CdTe NCs, crystal growth, defect passivation, photocarrier dynamics, and device performance are systematically investigated. We demonstrate that the surface trap states of as‐prepared aqueous CdTe NCs can be effectively passivated by introducing Cl ions in the synthetic process. In addition, it is discovered that Cl in the as‐prepared CdTe NCs can promote CdTe grain growth in the sintered process to reduce grain boundaries. The aqueous‐processed poly(p‐phenylenevinylene) (PPV)/CdTe HSCs are used as prototype solar cells to systematically study the influence of Cl on the electrical properties of CdTe NCs. The power conversion efficiency (PCE) of the HSCs based on CdTe NCs with optimal Cl content is improved by a factor of 25 compared to that based on the CdTe NCs without Cl. The ultrafast transient absorption (TA), transient photovoltage (TPV) and light intensity dependent open circuit voltage (Voc) and short‐circuit current density (Jsc) measurements are implemented to systematically investigate the influence of Cl on photocarrier dynamics, including charge transfer, lifetime, and carrier recombination. The researches on carrier recombination indicate that the presence of Cl can effectively reduce nongeminate recombination to improve charge extraction efficiency, thus leading to elevated device performance. Furthermore, it is demonstrated that the residual Cl after annealing also plays important roles in the highly efficient polymer/CdTe HSCs by passivating the trap states on the grain boundaries of CdTe NCs. Finally, this work suggests that the photovoltaic performance of HSCs can be further promoted through adopting improved passivation methods to reduce trap states on the grain boundaries in the future work.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Aqueous‐Processed Polymer/Nanocrystals Hybrid Solar Cells: The Effects of Chlorine on the Synthesis of CdTe Nanocrystals, Crystal Growth, Defect Passivation, Photocarrier Dynamics, and Device Performance

et al. 2017

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“…[31,32] As shown in Figure 4d, the decay dynamics of ZnO:CdTe film are faster, which means better electron extraction efficiency compared with TiO 2 :CdTe films. [31,32] As shown in Figure 4d, the decay dynamics of ZnO:CdTe film are faster, which means better electron extraction efficiency compared with TiO 2 :CdTe films.…”

mentioning

confidence: 93%

Highly Efficient Aqueous‐Processed Hybrid Solar Cells: Control Depletion Region and Improve Carrier Extraction

Chen

Jin

Wang

et al. 2019

Advanced Energy Materials

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on poly(p-phenylenevinylene) (PPV) and CdTe nanocrystals (NCs) was developed. [2] This work demonstrated the important influence of hybrid on the performance of solar cells based on aqueous process, encouraging us to further investigate the ASCs with a new configuration.However, the performance of the ASCs is still severely limited by the narrow width of the depletion region, the intrinsic defects of NCs, and the low carrier extraction ability, resulting in low short-circuit current (J sc ) and open voltage (V oc ) as well as a poor fill factor (FF). Many methods including passivating the surface of NCs, [3][4][5] high temperature annealing, [6] designing polymer with novel structure, [2,[7][8][9][10][11] optimizing device architecture, [12][13][14] etc. are developed to address these issues. For example, Wei et al. successfully designed conjugated polymer with high carrier mobility and largely improved device performance. [15] Jin et al. achieved a record PCE of 5.64% (as reported) based on PPV and CdTe NCs by optimizing device structure. [16] However, controlling the width of the depletion region and enhancing carrier extraction ability have been long a challenge.To address these issues, our group further developed an effective strategy that introduced different BHJ structure into the active material. The highest PCE as high as 6.01% was achieved based on ASCs. [17] In that work, one BHJ is consisted of CdTe and TiO 2 NCs and the other is CdTe NCs and PPV. The width of the depletion region and carrier extraction ability were significantly improved compared to previous works. As known, within limits, the thicker the BHJ film is, the better the performance is. In organic solar cells, the BHJ thickness can even reach 210 nm. [18] For aqueous-processed hybrid solar cells (AHSCs), however, the optimum thickness of the CdTe:TiO 2 BHJ film is only ≈30 nm in the double-side bulk heterojunction system mentioned above. In order to increase the BHJ film thickness and form the bicontinueous phase, the content of TiO 2 NCs have to be enhanced because of their small size. However, TiO 2 NCs contribute no photocurrent in the range of visible light and hence further increasing the thickness of BHJ film leads to the decrease of J sc . Although employing TiO 2 NCs with a larger size can obtain a thicker BHJ film and alleviate the decrease of J sc in theory, preparing water-soluble annatase TiO 2 with larger size is difficult and the aggregation occurs during Environmental friendly aqueous-processed solar cells have become one of the most promising candidates for the next-generation photovoltaic devices. Researchers have made lots of progress in designing active materials with novel structures, manipulating the defects in active materials, optimizing device architecture, etc. However, it has long been a challenge to control the width of the depletion region and enhance carrier extraction ability. Fabrication of a thick bulk heterojunction (BHJ) film is an effective strategy to address these issues but difficult to realize. Herein...

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“…Polymer/nanocrystals hybrid solar cells (HSCs) are one of the most promising candidates due to the combination of the light weight, mechanical flexibility characteristics of polymers and the broad absorption, high carrier mobility, and superior stability of inorganic nanocrystals . In order to achieve an environmental‐friendly production process, HSCs consist of water‐soluble polymers and aqueous CdTe nanocrystals are fabricated by our group, which shows a competitive development in recent years . By optimizing device structure and designing novel materials, the power conversion efficiencies (PCEs) of HSCs in both solvents and water have been improved to 5.5% …”

Section: Introductionmentioning

confidence: 99%

Constructing Post‐Permeation Method to Fabricate Polymer/Nanocrystals Hybrid Solar Cells with PCE Exceeding 6%

Zeng

Jin

et al. 2017

Small

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A post-permeation method is constructed for fabricating bulk-heterojunction hybrid solar cells. Porous CdTe film is prepared by annealing the mixture solution of aqueous CdTe nanocrystals and cetyltrimethyl ammonium bromide, after which the post-permeation of polymer is employed. By this method, kinds of polymers can be applied regardless of the intermiscibility with the nanoparticles. The inorganic nanocrystals and the polymer can be treated under respective optimized annealing temperatures, which can facilitate the growth of nanocrystals without damaging the polymers. A high power conversion efficiency of 6.36% in the polymer/nanocrystals hybrid solar cells is obtained via systematical optimization.

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Unravelling the working junction of aqueous-processed polymer–nanocrystal solar cells towards improved performance

Cited by 16 publications

References 43 publications

Aqueous‐Processed Polymer/Nanocrystals Hybrid Solar Cells: The Effects of Chlorine on the Synthesis of CdTe Nanocrystals, Crystal Growth, Defect Passivation, Photocarrier Dynamics, and Device Performance

Aqueous‐Processed Polymer/Nanocrystals Hybrid Solar Cells: The Effects of Chlorine on the Synthesis of CdTe Nanocrystals, Crystal Growth, Defect Passivation, Photocarrier Dynamics, and Device Performance

Highly Efficient Aqueous‐Processed Hybrid Solar Cells: Control Depletion Region and Improve Carrier Extraction

Constructing Post‐Permeation Method to Fabricate Polymer/Nanocrystals Hybrid Solar Cells with PCE Exceeding 6%

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