《太阳能电池原理及概论》讲义

太陽是能源之母 ■太陽是地球上所有能源的源頭’目前已知的能源幾 Solar cell introduction 乎都直接或間接來自太陽 石油丶煤丶天然氣丶水力丶太陽能丶風力丶光合作 用丶海洋能等等’核能丶地熱除外 ■太陽光照射整個地球表面1小時內的能量(-5×1020 J),約可供全人類使用1年 ■太陽逯可以繼續發光至少50億年以上。 林義成 ■太陽能是免費丶取之不盡丶用之不竭之潔浄能源 彰化師範大學機電系顯示所 但必須找到有效的使用法 全球再生能源發展機會 2000到2100年全球主要能源需求预测 這張合成圖片向我們呈現出地球夜晚的樣子 城市的燈光輝映出我們這個星球比敦繁榮的區域 lat Therma 口 Biomass ( modern Natral Gas Source: German Advisory Council on Global Change, 2003

Solar Cell Introduction 林義成 彰化師範大學 機電系/顯示所 2 太陽是能源之母 „ 太陽是地球上所有能源的源頭，目前已知的能源幾 乎都直接或間接來自太陽。 – 石油、煤、天然氣、水力、太陽能、風力、光合作 用、海洋能等等，核能、地熱除外。 „ 太陽光照射整個地球表面1小時內的能量(~5×1020 J)，約可供全人類使用1 年。 „ 太陽還可以繼續發光至少50 億年以上。 „ 太陽能是免費、取之不盡、用之不竭之潔淨能源， 但必須找到有效的使用法。 3 全球再生能源發展機會 ‧這張合成圖片向我們呈現出地球夜晚的樣子 ‧城市的燈光輝映出我們這個星球比較繁榮的區域 4 2000到2100年全球主要能源需求預測

太陽光發電之重要歷史 太陽能的形成 1954年 Bell labs發展出矽太陽電池( Chapin等人’轉换效 率约4.5%) 1956年第一個太陽電池製作成功 1500780400160 1958年開始太空應用(GaAs) 1970年開始太陽光發電糸統地面應用(S〕(能源危機) ■1976年 Carlson製作出第一個非晶薄膜太陽電池 ■1980年消費性薄膜太陽電池應用(aSi,CdS/CdTe) ■1990年與公用電力併聯之太陽光發電系統技衙成熟(Gnd- Connected PV System,Si)(電力電子技衙) 1992年起歐美丶日各國推動PV補助獎勵 2000年建材一體型太陽電池應用(BIPV) 5 /旦/了 Solar Spectrum 太陽空氣質量( Air mass) a The spectrum as seen from satellite is referred to as aMO AM= PPo a secB spectrum, and closely fits the spectrum of a blackbody at 5800 B ZENITH ANGLE K The total Density is 1353 W/cm. The solar spectrum as observed on earth is modified due to absorption in atmosphere For AMI (normal incident), the power density is reduced to 925 W/cm where as for AM1.5 (45 Above the horizon) the power is 844 W/cm Intesity Is Wcm(unr 太陽空氣質量(A)輻射單位及其入射角定義示意閩 04060810121416120 Wavelength (um)

5 太陽光發電之重要歷史 „ 1954年Bell Labs發展出矽太陽電池 (Chapin等人，轉換效 率約4.5%) „ 1956年第一個太陽電池製作成功 „ 1958年開始太空應用(GaAs) „ 1970年開始太陽光發電系統地面應用(Si) (能源危機) „ 1976年Carlson製作出第一個非晶薄膜太陽電池 „ 1980年消費性薄膜太陽電池應用(a-Si, CdS/CdTe) „ 1990年與公用電力併聯之太陽光發電系統技術成熟(Grid￾Connected PV System, Si) (電力電子技術) „ 1992年起歐美、日各國推動PV補助獎勵 „ 2000年建材一體型太陽電池應用(BIPV) 6 太陽能的形成 7 Solar Spectrum „ The spectrum as seen from satellite is referred to as AM0 spectrum, and closely fits the spectrum of a blackbody at 5800 K. The total power Density is 1353 W/cm2. The solar spectrum as observed on earth is modified due to absorption in atmosphere. For AM1 (normal incident), the power density is reduced to 925 W/cm2, where as for AM1.5 (45oAbove the horizon) the power is 844 W/cm2. 8 太陽空氣質量(Air Mass)

太陽能發電應用 The Large concentrated pv system PV系锍容量:1.7M (Sonnen, Bayern, Germany) 太陽能發電魔用 太陽能發電鹿用

9 太陽能發電應用 10 The Large Concentrated PV System (Sonnen, Bayern, Germany) PV系統容量：1.7 MW 11 太陽能發電應用 12 太陽能發電應用

太陽能發電應用 Building Integrated Photovoltaics (BIPV) Summer Winter BPV應用 BPV應用

13 太陽能發電應用 14 Building Integrated Photovoltaics (BIPV) 15 BIPV應用 16 BIPV應用

太陽能發電應用 太陽光電糸統在落後地區的應用 南非獨立型太陽光電系统應用在 通訊 太陽光電系统在印度汲水應用 太陽光電在沙漠上的應用 太陽能電池的工作原理

17 太陽能發電應用 太陽光電系統在印度汲水應用 南非獨立型太陽光電系統應用在 通訊 18 太陽光電系統在落後地區的應用 19 太陽光電在沙漠上的應用 太陽能電池的工作原理

太陽能電池的工作原理 Semiconductor-Energy band 射防止膜 Refed-Proof Film 型半哪 N-Type Semiconduct :。sm Energy aap Sp甲 D半海曾 p-Type Semiconductor I we far apart atoms Iwe close atoms 太光鼋粒子 A K Cha, Nated Sun Ya-sen Univers Semiconductor -Fermi level Semiconductor -Drift and diffusion At thermal equilibriu, Fermi function describes hss action lay the probability that a state at energy E Is nilled by Diffusion where Ey b a refereace energy called HDPe LE,E, Energy lasses due to eel states at energy E whih are less than Er are mostly nlle: States at energy E which are larger than Er are mostly unoccupied. EE+ d 0 d Carier concentrations in conduction band and E valence bands are E,MMm“t4rd= where 一gErn=v D,=-4: Diffusa eeeficirat J=∑-=-=啊只E N-2 25m yx Efecthe dreary f tate of rance ad 口J= A k Chu Natal Sun Ya sen Unverse A.K. Cha, Natonal Sun Ya-sen Universty

21 太陽能電池的工作原理 22 Semiconductor-Energy band A. K. Chu, National Sun Yat-sen University 23 Semiconductor-Fermi level A. K. Chu, National Sun Yat-sen University 24 Semiconductor-Drift and diffusion A. K. Chu, National Sun Yat-sen University

Semiconductor- pn homojunction Depletion region width Forward bias N., n intrinsic carrier density r,=r, tr E w n, for Si is 1 45xl0cm =+,mV0 imbrium, the Fermi-leel Example A lightly doped, n-type Si has a resistivity 几 Reverse bias higher than that in then-type Si What is the build. Forward bias,3,\ 南, in voltage at the junction E.5 For a resistivity of 4@2-cm,\, =105 cr. e, for Si is 11.7, and t-8.854x10 Fcm dMMN, =0.753 Depletion region width: x“x 125(+=0=10 A.K. Chu, Natonal Sun Yasen Unversity A K Cha, Nated Sun Ya-sen Univers Photovoltaic effect Operation of photovoltaic device Si Energy band diagram a The operation of the photovoltaic device follows v-o(thermal eguilibrium by D e-h pairs creation by photons absorption D Separation of e-h pairs before recombination n Transportation of free e and h to electrodes +V=% Flat band count Heat <<KI A k Chu Natal Sun Ya sen Unverse

25 Semiconductor- pn homojunction A. K. Chu, National Sun Yat-sen University 26 A. K. Chu, National Sun Yat-sen University 27 Photovoltaic effect A. K. Chu, National Sun Yat-sen University 28 Operation of photovoltaic device(I) „ The operation of the photovoltaic device follows by … e-h pairs creation by photons absorption … Separation of e-h pairs before recombination … Transportation of free e and h to electrodes

Operation of photovoltaic device () Operation of photovoltaic device(l) Transportation Carrier recombination Quasi-neutral region Diffusion length, L, Carriers move by difFusion L, "D, p Carrier recombination carrier lifetime of hole Use, cm Quasi-neutral [Depletion: Quasi-neutral Quasi-neutral Depletion; Quasi-neutral D,-12(m/sec eglon Carriers move by drifting A.K. Chu, Natonal Sun Yasen Unversity A K Cha, Nated Sun Ya-sen Univers Fundamentals Metal-semiconductor contact e Photovoltaic effect results from_f Band diagram of metal-semiconductor interface incident light on some materials n-setnicondurter , PV effect promotes electrons higher energy conduction ban leaving holes behind . Separation of carriers, electrons ve)and holes(+ve)important to solar cells , +ve and-ve carriers transported fn"h x through material in all directions will now from K Ch, Natoma Sun Yasn Unrversty

29 Operation of photovoltaic device(II) A. K. Chu, National Sun Yat-sen University 30 Operation of photovoltaic device(III) A. K. Chu, National Sun Yat-sen University 31 Fundamentals ™ Photovoltaic effect results from incident light on some materials ™ PV effect promotes electrons into higher energy conduction bands, leaving holes behind ™ Separation of carriers, electrons (- ve) and holes (+ve) important to solar cells ™ +ve and –ve carriers transported through material in all directions Surface recombination Surface recombination Bulk recombination 32 Metal-semiconductor contact A. K. Chu, National Sun Yat-sen University

Tunneling contact Alloying contact Contact metals shottky barriers to si E N E E silicon type Metal q%r(eV) q%(ev) E x= 24 (9-2 N,4 A.K. Chu, Natonal Sun Yasen Unversity 串聯與分流(並聯)電阻 太陽能電池的等效電路 串聯電 R Pegler ■Rp分流(並聯)電 阻 lectrode ph RL Solar cell

33 A. K. Chu, National Sun Yat-sen University 34 35 串聯與分流(並聯)電阻 „ Rs:串聯電阻 „ Rp:分流(並聯)電 阻 36 太陽能電池的等效電路

串聯電阻會使V曲錢變寬 The Laws of Geometric Optics ■串聯電阻會使曲縵 tght travel in a straight line in a medium with constant n. 變寬 Incident angle of a light is equal to the reflection angle of the light. 口降低最大可能功率 Refraction (Snell's law) 口使得太陽能電池的 整體效率降低 ■Rs不會影響開路電 R=20日 Example n2“L,n2“15anda-3 Dielectric constant &=6,'s, 壓Voc,但低的Rp Pane ef incident 值會使Ⅴoc降低 xsm30°=15winb A K Cha, Nated Sun Ya-sen Univers Reflection and refraction of waves Reflection of Lights at Different Surfaces The direction of light propagation can be altered index of the medium

37 串聯電阻會使I-V曲綫變寬 „ 串聯電阻會使曲綫 變寬 … 降低最大可能功率 … 使得太陽能電池的 整體效率降低。 „ Rs不會影響開路電 壓Voc，但低的Rp 值會使Voc降低 38 The Laws of Geometric Optics A. K. Chu, National Sun Yat-sen University 39 Reflection and Refraction of Waves 40 Reflection of Lights at Different Surfaces