Precursor designs for Cu₂ZnSn(S,Se)₄ thin-film solar cells

Yang, Kee-Jeong,Sim, Jun-Hyoung,Son, Dae-Ho,Kim, Young-Ill,Kim, Dae-Hwan,Nam, Dahyun,Cheong, Hyeonsik,Kim, SeongYeon,Kim, JunHo,Kang, Jin-Kyu unknown 2017 Nano energy Vol.35 No.-

<P><B>Abstract</B></P> <P>To commercialize Cu<SUB>2</SUB>ZnSn(S,Se)<SUB>4</SUB> (CZTSSe) thin-film solar cells, it is necessary to improve their efficiency and to develop the technological ability to produce large-area modules. Defect formation due to the secondary phase is considered to be one of the main reasons for decreased CZTSSe thin-film solar-cell efficiency. This study explores the potential capabilities of large-area thin-film solar cells by controlling the defect formation using various CZTSSe precursor designs, and by improving the characteristic uniformity within the thin-film solar cells. Alloying the precursor as a stack of discrete layers can result in lateral segregation of elements into stable-phase islands, yielding a non-uniform composition on small length scales. It is found that the application of an indiscrete layer by minimizing the precursor-layer thickness allows avoiding Zn rich inhomogeneities in the absorber that would favor formation of detrimental ZnS-ZnSe secondary phases and deep defects. Among the various precursor layers designed by considering the reaction mechanism under annealing, a sample with 15 precursor layers is found to exhibit a shallow electron-acceptor energy level, high photovoltaic conversion efficiency, and uniform characteristics over the corresponding thin-film solar cell. Based on such improvements in both the efficiency and characteristic distribution, it is expected that the commercialization of CZTSSe thin-film solar cells can be advanced.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An indiscrete layer enabled the suppression of the overly rich Zn zone. </LI> <LI> It prevents the formation of Zn-rich detrimental secondary phases and defects. </LI> <LI> A sample with 15 precursor layers exhibits a shallow acceptor energy level. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>An indiscrete layer was chosen as a precursor stacking order design, which enabled the suppression of the overly rich Zn zone during a relatively low-temperature annealing process, thus preventing the formation of Zn-rich detrimental secondary phases and defects in these regions. A higher PCE and a uniform composition ratio distribution, which helped to realize uniform characteristics across the solar cell, were obtained.</P> <P>[DISPLAY OMISSION]</P>

표면 플라즈몬 효과를 이용한 박막형 태양전지 효율향상

변수환 ( Soo Hwan Byun ),소현준 ( Hyun Jun Soh ),유정훈 ( Jeong Hoon Yoo ) 정보저장시스템학회 2012 정보저장시스템학회논문집 Vol.8 No.2

In spite of many advantages, the practical application of the thin film solar cell is restricted due to its low efficiency compared with the bulk type solar cells. This study intends to adopt the surface plasmon effect using nano particles to solve the low efficiency problem in thin film solar cells. By inserting Ag nano-particles in the absorbing layer of a thin film solar cell, the poynting vector value of the absorbing layer is increased due to the strong energy field. Increasing the value may give thin film solar cells chance to absorb more energy from the incident beam so that the efficiency of the thin film solar cell can be improved. In this work, we have designed the optimal shape of Ag nano-particle in the absorbing laser of a basic type thin film solar cell using the finite element analysis commercial package COMSOL. Design parameters are set to the particle diameter and the distance between each Ag nano-particle and by changing those parameters using the full factorial design variable set-up, we can determine optimal design of Ag nano-particles for maximizing the poynting vector value in the absorbing layer.

모듈 형태별 태양광 발전 비교 실증 분석

박재환,박준훈 사단법인 인문사회과학기술융합학회 2016 예술인문사회융합멀티미디어논문지 Vol.6 No.11

Solar power generation has been a renewable energy that have large electric capacity and long life spans. There are different kinds depending on the form and function of solar module and the characteristics of the types are different. In this study, the electrical efficiency of several photovoltaic modules (crystalline solar-cell and thin-film solar-cell) under different driving condition (fixed and tracking) was studied. The maximum electrical power output of modules were 107% (crystalline solar-cell / tracking), 107% (crystalline solar-cell / fixed), and 72% (thin-film solar-cell / fixed). The electric power generation time of modules were 7.8h (crystalline solar-cell / tracking), 4.2h (thin-film solar-cell / fixed), and 6.3h (crystalline solar-cell / fixed). The overall electric performance of the thin film module was rather low, which could be attributed to the efficiency degradation after module fabrication. Electric power generation reaches from Mar. to Apr. when the solar radiation is quite enough and the ambient temperature is rather low. 태양광발전은 수명이 길고 발전용량이 큰 신재생에너지이다. 태양전지 모듈은 형태와 기능에 따라 다양한 종류가 있으며, 각각의 발전 특성이 다르다. 본 연구에서는 태양전지 모듈의 종류 (결정질, 박막) 및 구동방식 (추적식, 고정식)의 변화에 따른 발전 특성을 조사하였다. 시설용량 대비 최대 순간 발전량은 결정질 Si (양축식) 107%, 결정질 Si (고정식) 107%, 박막 Si (고정식) 72%로 나타났다. 일일 최대 발전시간은 결정질 Si (양축식) 7.8시간, 박막 Si (고정식) 4.2시간, 결정질 Si (고정식) 6.3시간으로 나타났다. 전체적으로 박막 모듈의 발전 성능이 떨어지는 것은 박막 모듈 제조 이후 시간경과에 따른 효율 저하율이 크기 때문인 것으로 판단된다. 태양광 추적형 (양축식) 모듈은 시스템이 복잡한 단점이 있으나, 고정식 모듈에 비하여 24% 정도 더 우수한 발전량을 나타내었다. 태양광 발전이 최대가 되는 시기는 3~4월이며, 이는 일사량이 어느 정도 보장되면서 외기 온도가 낮은 기후적 특성에 기인하는 것으로 보인다.

Highly transparent and conductive oxide-metal-oxide electrodes optimized at the percolation thickness of AgO_x for transparent silicon thin-film solar cells

Jo, Hyunjin,Yang, Jo-Hwa,Choi, Soo-Won,Park, Jaeho,Song, Eun Jin,Shin, Myunhun,Ahn, Ji-Hoon,Kwon, Jung-Dae Elsevier 2019 Solar energy materials and solar cells Vol.202 No.-

<P><B>Abstract</B></P> <P>Highly transparent and conductive oxide-metal-oxide (OMO) electrodes comprising aluminum-doped zinc-oxide (AZO) and ultrathin Ag or oxygen (O<SUB>2</SUB>)-doped Ag (AgO<SUB>x</SUB>) metal layers were fabricated for use in thin-film silicon solar cells. The surface morphologies of the metal layers and the transparencies and conductivities of OMO electrodes were investigated near the percolation thickness values of the metal layers. The percolation metal thickness, which means the metal layer is morphologically continuous, could be used to optimize the transparent OMO electrode. Additionally, thin Ag-based OMO (AgO<SUB>x</SUB> OMO) with superior performance could be fabricated by adding O<SUB>2</SUB>. The optimized AgO<SUB>x</SUB> OMO electrodes yielded the highest average transmittance (<I>T</I> <SUB>avg</SUB>) of 93.5% and the lowest average optical loss (OL<SUB>avg</SUB>) of 1.01% within 500–800 nm at the percolation thickness of ~6 nm, thus, maintaining low conductivity. These outcomes were superior to the responses of the percolated Ag OMO (<I>T</I> <SUB>avg</SUB> = 87.2%; OL<SUB>avg</SUB> = 1.01%). Using the OMO structure at the rear electrode, transparent hydrogenated amorphous silicon thin-film solar was fabricated for building integrated photovoltaic windows. The best figure-of-merit (FOM; equal to the product of <I>T</I> <SUB>avg</SUB> and efficiency <I>η</I>) values of the OMO-based transparent solar cells could be obtained for percolated OMO structures. The cells using AgO<SUB>x</SUB> OMO (AgO<SUB>x</SUB> cells) performed better than the Ag cells; the best FOMs of AgO<SUB>x</SUB> and Ag cells were 140.8 (<I>T</I> <SUB>avg</SUB> = 27.8%; <I>η</I> = 5.51%) and 104.6% (<I>T</I> <SUB>avg</SUB> = 18.9%; <I>η</I> = 5.54%), respectively. These results could contribute to the development of high-performance transparent solar cells or optoelectronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Transparent/conductive oxide-metal-oxide (OMO) electrodes were fabricated. </LI> <LI> Oxygen doping effects in thin Ag film is investigated. </LI> <LI> Optimization of OMO electrodes was based on the percolation metal thickness. </LI> <LI> Thin oxygen-doped Ag-based OMO electrodes yielded better performances. </LI> <LI> Optimized electrodes can be used in high-performance transparent solar cells/devices. </LI> </UL> </P>

In과 Ga가 미포함 된 Kesterite Cu₂ZnSn(S_1-x,Se_x)₄ (CZTSS) 박막형 태양전지 개발 현황

신승욱,한준희,강명길,윤재호,이정용,김진혁,Shin, Seung-Wook,Han, Jun-Hee,Gang, Myeng-Gil,Yun, Jae-Ho,Lee, Jeong-Yong,Kim, Jin-Hyeok 한국재료학회 2012 한국재료학회지 Vol.22 No.5

Chalcogenide-based semiconductors, such as $CuInSe_2$, $CuGaSe_2$, Cu(In,Ga)$Se_2$ (CIGS), and CdTe have attracted considerable interest as efficient materials in thin film solar cells (TFSCs). Currently, CIGS and CdTe TFSCs have demonstrated the highest power conversion efficiency (PCE) of over 11% in module production. However, commercialized CIGS and CdTe TFSCs have some limitations due to the scarcity of In, Ga, and Te and the environmental issues associated with Cd and Se. Recently, kesterite CZTS, which is one of the In- and Ga- free absorber materials, has been attracted considerable attention as a new candidate for use as an absorber material in thin film solar cells. The CZTS-based absorber material has outstanding characteristics such as band gap energy of 1.0 eV to 1.5 eV, high absorption coefficient on the order of $10^4cm^{-1}$, and high theoretical conversion efficiency of 32.2% in thin film solar cells. Despite these promising characteristics, research into CZTS-based thin film solar cells is still incomprehensive and related reports are quite few compared to those for CIGS thin film solar cells, which show high efficiency of over 20%. The recent development of kesterite-based CZTS thin film solar cells is summarized in this work. The new challenges for enhanced performance in CZTS thin films are examined and prospective issues are addressed as well.

New Generation Multijunction Solar Cells for Achieving High Efficiencies

이선화,박진주,김영국,김상호,S. M. Iftiquar,이준신 한국태양광발전학회 2018 Current Photovoltaic Research Vol.6 No.2

Multijunction solar cells present a practical solution towards a better photovoltaic conversion for a wider spectral range. In this review, we compare different types of multi-ijunction solar cell. First, we introduce thin film multijunction solar cell include to the thin film silicon, III-V material and chalcopyrite material. Until now the maximum reported power conversion efficiencies (PCE) of solar cells having different component sub-cells are 14.0% (thin film silicon), 46% (III-V material), 4.4% (chalcopyrite material) respectively. We then discuss the development of multijunction solar cell in which c-Si is used as bottom sub-cell while III-V material, thin film silicon, chalcopyrite material or perovskite material is used as top sub-cells.

Effect of sulfurization temperature on the efficiency of SnS solar cells fabricated by sulfurization of sputtered tin precursor layers using effusion cell evaporation

Minnam Reddy, Vasudeva Reddy,Cho, Haeyun,Gedi, Sreedevi,Reddy, K.T. Ramakrishna,Kim, Woo Kyoung,Park, Chinho Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.806 No.-

<P><B>Abstract</B></P> <P>Earth-abundant tin monosulfide (SnS) thin films have attracted considerable interest for eco-friendly and low-cost thin film solar cells. However, less attention has been paid on the fabrication of SnS solar cell by the industrial processes. In view of that the current study aimed to fabricate the SnS solar cells via two-stage (sputtering + sulfurization) industrial process. For the preparation of SnS thin films, first tin metallic precursor layers were deposited by DC sputtering and then sulfurized using the rapid thermal effusion cell evaporation process. The effect of sulfurization temperature on the physical properties of SnS thin films and the efficiency of SnS solar cells was examined. Formation of the single phase SnS thin films was confirmed when the tin metallic precursor layers sulfurized in the range of 450–470 °C, whereas secondary phases of Sn, SnS<SUB>2</SUB>, and Sn<SUB>2</SUB>S<SUB>3</SUB> were noticed at the sulfurization temperature lower than 450 °C and re-evaporation of deposited SnS thin films was observed at the sulfurization temperature higher than 470 °C. Solar cell fabricated with SnS absorber sulfurized at a temperature of 470 °C showed the conversion efficiency of ∼ 2.3%. The causes for lower efficiency of these solar cells were recombination in the SnS absorber and non-uniform compositional distribution of Cd, S and Sn as a function of depth in the CdS/SnS/Mo structure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SnS films were grown via sulfurization using effusion cell evaporation method. </LI> <LI> Effect of sulfurization temperature on the efficiency of SnS solar cells was examined. </LI> <LI> A high efficiency of ∼2.3% for SnS solar cells was achieved at 470 °C. </LI> <LI> The causes for lower efficiency of these solar cells were investigated. </LI> </UL> </P>

그라파이트 기판을 이용한 유연 박막 실리콘 태양전지 특성 향상

임경열,조준식,장효식,Lim, Gyeong-yeol,Cho, Jun-sik,Chang, Hyo Sik 한국재료학회 2019 한국재료학회지 Vol.29 No.5

We investigated the characteristics of nano crystalline silicon(nc-Si) thin-film solar cells on graphite substrates. Amorphous silicon(a-Si) thin-film solar cells on graphite plates show low conversion efficiency due to high surface roughness, and many recombination by dangling bonds. In previous studies, we deposited barrier films by plasma enhanced chemical vapor deposition(PECVD) on graphite plate to reduce surface roughness and achieved ~7.8 % cell efficiency. In this study, we fabricated nc-Si thin film solar cell on graphite in order to increase the efficiency of solar cells. We achieved 8.45 % efficiency on graphite plate and applied this to nc-Si on graphite sheet for flexible solar cell applications. The characterization of the cell is performed with external quantum efficiency(EQE) and current density-voltage measurements(J-V). As a result, we obtain ~8.42 % cell efficiency in a flexible solar cell fabricated on a graphite sheet, which performance is similar to that of cells fabricated on graphite plates.

박막 실리콘 태양전지의 광열화현상 연구: 비정질 실리콘 태양전지 및 나노양자점 실리콘 박막 태양전지

김가현 한국태양에너지학회 2019 한국태양에너지학회 논문집 Vol.39 No.1

Light induced degradation is one of the major research challenges of hydrogenated amorphous silicon related thin film silicon solar cells. Amorphous silicon shows creation of metastable defect states, originating from elevated concentration of dangling bonds during light exposure. The metastable defect states work as recombination centers, and mostly affects quality of intrinsic layer in solar cells. In this paper we present results of light induced degradation in thin film silicon solar cells and discussion on physical origin, mechanism and practical solutions of light induced degradation in thin film silicon solar cells. In-situ light-soaking IV measurement techniques are presented. We also present thin film silicon material with silicon nano-quantum dots embedded within amorphous matrix, which shows superior stability during light-soaking. Our results suggest that solar cell using silicon nano-quantum dots in abosrber layer shows superior stability under light soaking, compared to the conventional amorphous silicon solar cell.

Robust nanoscale contact of silver nanowire electrodes to semiconductors to achieve high performance chalcogenide thin film solar cells

Lee, Sangyeob,Lee, Jun Su,Jang, Jiseong,Hong, Ki-Ha,Lee, Doh-Kwon,Song, Soomin,Kim, Kihwan,Eo, Young-Joo,Yun, Jae Ho,Gwak, Jihye,Chung, Choong-Heui Elsevier 2018 Nano energy Vol.53 No.-

<P><B>Abstract</B></P> <P>We demonstrate the ability to fabricate high-quality nanoscale electrical contact between silver nanowires (AgNWs) and underlying semiconducting layers in chalcogenide thin film solar cells. AgNW electrodes have attracted many interests due to their ability for low temperature solution processing. However, they have a drawback that the interfacial defects can be generated between AgNWs and underlying rugged semiconductor layers making it difficult to form high-quality junction. To enhance the junction properties, conducting matrix layers have been adapted. Yet, the issues regarding the AgNW/semiconductor junction have not been fully resolved. We developed a facile method to form robust nanoscale contact between AgNWs and semiconducting thin films to achieve high performance chalcogenide thin film solar cells. The method is to deposit an ultra-thin semiconductor layer on devices using aqueous chemical bath deposition. The chemical bath deposition has capability to effectively fill even nanoscale gap and to form chemically stable bonds as well as an intimate junction. As a proof of concept, a CdS layer (~ 10 nm) was deposited using the chemical bath deposition on Cu(In,Ga)Se<SUB>2</SUB> (CIGS) solar cells with a structure of AgNW/CdS/CIGS/Mo/Glass. We also identified that the key factor governing the current-voltage characteristic is the electrical contact between the AgNW electrode and the CdS buffer layer in CIGS thin film solar cells. The power conversion efficiency of the CIGS cell was dramatically improved from 4.9% to 14.2% owing to high-quality AgNW-CdS electrical contact produced by chemical bath deposition of the additional CdS layer as thin as 10 nm.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A facile method to form robust nanoscale contact between AgNWs and semiconductors for high performance solar cell. </LI> <LI> Formation of high quality junction between AgNWs and a CdS buffer layer in CIGS solar cells by chemical bath deposition. </LI> <LI> Due to the high quality contact, the efficiency of CIGS solar cells dramatically improves from 4.9% to 14.2%. </LI> <LI> The cells with high quality junction show high performance at any illumination conditions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>