In Situ Construction of Nanoscale CdTe‐CdS Bulk Heterojunctions for Inorganic Nanocrystal Solar Cells

Chen, Zhaolai; Zhang, Hao; Zeng, Qingsen; Wang, Yan; Xu, Dandan; Wang, Lei; Li, Ang; Yang, Bai

doi:10.1002/aenm.201400235

Cited by 44 publications

(43 citation statements)

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“…[1][2][3] To date, III-V NCs including PbS, 4 PbSe 5 and PbS x Se 1Àx (ref. On the other hand, solar cells based on sintering NCs such as CuInS 2 , 7 CuInSe 2 8 and CdTe [9][10][11][12][13][14][15] have also been investigated and good device performances have been obtained. On the other hand, solar cells based on sintering NCs such as CuInS 2 , 7 CuInSe 2 8 and CdTe [9][10][11][12][13][14][15] have also been investigated and good device performances have been obtained.…”

Section: Introductionmentioning

confidence: 99%

Solution processed CdTe/CdSe nanocrystal solar cells with more than 5.5% efficiency by using an inverted device structure

et al. 2015

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CdTe/CdSe nanocrystal (NC) solar cells with an inverted structure (ITO/ZnO/CdSe/CdTe/Au) have been successfully fabricated by a simple solution process coupled with layer-by-layer sintering techniques. It was found that the device performance is strongly dependent on the annealing strategy, the thickness of the acceptor layer and on the buffer layer of ZnO when the optimal thickness of CdTe is adopted. Without the ZnO buffer layer, a thin film of the CdSeNCs on an ITO substrate shows a rougher morphology, resulting in device shunting. However, when a 40 nm-thick ZnO buffer layer and 60 nm-thick CdSe were employed, the device shows a much higher PCE of 5.81% under device conditions, post-annealing at 340 8C. This value is the highest efficiency ever reported to date for a CdTe/CdSe NC solar cell. Comparing with CdTe/CdSe NC solar cells with the normal device configuration, this device with an inverted structure simultaneously offers good Ohmic contact for carrier collection and efficient harvesting of solar photons in a wide wavelength.

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Section: Introductionmentioning

confidence: 99%

Solution processed CdTe/CdSe nanocrystal solar cells with more than 5.5% efficiency by using an inverted device structure

et al. 2015

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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. [2,5,[7][8][9]13,15,17,[33][34][35][36][37][38][39][40] It is shown that the highest PCE (6.51%) and J sc (19.5 mA cm −2 ) have been obtained in this work. As a result, the probability of carrier recombination process becomes smaller.…”

mentioning

confidence: 54%

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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“…The TiO 2 precursors are prepared according to a previous work . In brief, 4 mL tetrabutyl titanate (TBT) is dissolved in 2 mL isopropanol in a clean conical flask.…”

Section: Methodsmentioning

confidence: 99%

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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In Situ Construction of Nanoscale CdTe‐CdS Bulk Heterojunctions for Inorganic Nanocrystal Solar Cells

Cited by 44 publications

References 46 publications

Solution processed CdTe/CdSe nanocrystal solar cells with more than 5.5% efficiency by using an inverted device structure

Solution processed CdTe/CdSe nanocrystal solar cells with more than 5.5% efficiency by using an inverted device structure

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

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

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