Читать книгу Physics of Thin-Film Photovoltaics - Victor G. Karpov - Страница 4

1 Part IFig. 1 Conceptual design of a solar cell. Front and back contacts are metallic, ...Fig. 2 Band diagram of a metal/semiconductor/metal structure where E_F1 and E_F2 r...Fig. 3 Diffusion of the photogenerated electrons and holes to the electrodes in ...Fig. 4 In thin film devices, drift rather than diffusion can determine the kinet...Fig. 5 Role of grain boundaries in noncrystalline thin film PV. Left: Sketch of ...Fig. 6 A cross-sectional view of a superstrate (glass sheet up) CdTe based and s...

2 Part IIFig. 7 Energy band diagram of a symmetric potential barrier separating two metal...Fig. 8 Current-voltage characteristic of a system with symmetric barrier illustr...Fig. 9 Energy band diagram of an asymmetric potential barrier between two differ...Fig. 10 Current voltage characteristic of a system with asymmetric barrier illus...Fig. 11 Schottky barrier formation: (a) No electric contact; the Fermi level is ...Fig. 12 Gap states due to electron tunneling from the metal to dielectric side c...Fig. 13 Reach-through structure of a semiconductor layer sandwiched between two ...Fig. 14 Metal-semiconductor-metal structure before field compensation (a) and af...Fig. 15 The real space and energy space diagrams for the classical p-n homojunct...Fig. 16 Possible band diagram alignments with positive, zero, and negative Condu...Fig. 17 A rough sketch of the commonly used band diagram for CdTe and CIGS based...Fig. 18 The schematic structure and band diagram of a p-i-n diode.Fig. 19 The electron energy and field distribution for a two-layer (A,B) system ...Fig. 20 Top: a photograph of cat’s whisker diode [32]. Bottom: electrostatic int...Fig. 21 (a) Sketch of the electric field lines in a system with thin ellipsoidal...Fig. 22 Zero bias band diagram of a metal-semiconductor-metal model of solar cel...Fig. 23 The essential domain of current voltage characteristic of a diode struct...Fig. 24 Towards understanding of the nature of open circuit voltage (V_oc). Dashe...Fig. 25 The measured temperature dependence of V_oc for a CdTe solar cell and its...Fig. 26 External quantum efficiencies for the baseline CdS/CdTe (older generatio...Fig. 27 AMPS modeled band diagrams for CdTe and CIGS based PV. Reproduces with p...Fig. 28 AMPS modeled current voltage characteristics for CdTe (left) and CIGS (r...Fig. 29 Left: AMPS modeled IQE for CdTe and CIGS based PV. Right: Corresponding ...Fig. 30 Left: Energy band diagram of a graded CIGS solar cell based on a Ga dept...Fig. 31 Left: SCAPS simulation of the I(V) curves of a CdS/CdTe/Au solar cell, f...Fig. 32 Definition of the fill factor (FF) as the ratio of the areas of the smal...Fig. 33 Exaggerated sketches of the light (red) and dark (black) current voltage...Fig. 34 Statistics of nonideality factor for CdTe solar cells of efficiency grea...Fig. 35 The equivalent circuit of a PV device including the shunt (R_sh) and seri...Fig. 36 Histograms of statistical distributions of fill factors and short circui...Fig. 37 (a) Left: The ‘weak diode’ circuit where one diode has significantly low...Fig. 38 (a) Ideal diode with a resistor in series. (b) Ideal diode with a parall...Fig. 39 Phenomenological interpretation of dark to light IV crossings. The circu...Fig. 40 Conceivable band diagrams of CdS based PV. (a) p-n structure with n-type...Fig. 41 Phenomenological model of CdS based thin-film PV. σ represents the two-d...Fig. 42 Left: AMPS simulated (a) vs. analytical (b) J-V characteristics for the ...Fig. 43 Left: AMPS simulated band diagram at thermal equilibrium; 3 × 10¹⁸ cm^-3 ...Fig. 44 Left: AMPS simulated band diagram at thermal equilibrium; where the acce...Fig. 45 ‘Hunch’ model characteristics. Left: AMPS simulated band diagram at ther...Fig. 46 AMPS generated light J – V characteristics and quantum efficiencies (QE)...Fig. 47 Band diagram of CdS based device corresponding to the case of “hunch mod...Fig. 48 Open circuit voltage (V_oc), short circuit current (J_sc), fill factor (FF...Fig. 49 Towards the effect of CdS leakiness on the integral device V_oc = V_oc2 − ...Fig. 50 (a) Current-voltage characteristics of the good back contact (Good BC) a...Fig. 51 (a) The band diagram of the main junction (left part) and a moderate (tr...

3 Part IIIFig. 52 (a) The equivalent circuit design of a 1D thin film solar cell; R can re...Fig. 53 The electric potential distributions in a semi-infinite one dimensional ...Fig. 54 The electric potential distribution in a dot cell under forward and reve...Fig. 55 An example of the current-voltage characteristic for an infinitely large...Fig. 56 The measured electric potential distributions (a) in a shunted PV strip ...Fig. 57 Multidimensional diagrams of Schottky barriers. x - axis points into the...Fig. 58 (a) A semi-shunt of length a < L in comparison with a dead metal shunt s...Fig. 59 The histograms of the open-circuit and short-circuit resistances showing...Fig. 60 (a) A representative IV curves of a ‘good’ and ‘bad’ (low V_oc) nominally...Fig. 61 Left: back metal deposited on the interfacial layer (IFL) will generate ...Fig. 62 Left: Current-voltage characteristics and equivalent circuit of a weak d...Fig. 63 Simulated open-circuit voltage (V_oc), electric potential (V), and transv...Fig. 64 Electric potential variations in a 2D system of random diodes numericall...Fig. 65 (a) Fluctuations of micro-diode V_ocs in real space. (b) Their probabilis...Fig. 66 Electric potential variations in a 2D system of random diodes numericall...Fig. 67 Integrated PV module (typical of CdTe based PV where individual linear c...Fig. 68 PSPICE simulation results demonstrating how different V_oc distributions,...Fig. 69 Effect of shunts and “holes” depending on their relative fraction in the...Fig. 70 PSPICE software circuit equivalent to that in Fig. 72. Figures represent...Fig. 71 Relative mismatch loss in efficiency is about 8 % for a moderate disorde...Fig. 72 Conceptual circuitry representations sketching the propagation of nonuni...Fig. 73 The principle design of electron beam induced current (EBIC) mapping (le...Fig. 74 Laser beam induced current (LBIC) data displayed as a map and as a histo...Fig. 75 (a) EL image taken at 640 mV forward bias with enhanced contrast to high...Fig. 76 Photoluminescence mapping of a solar cell before (left) and after (right...Fig. 77 Photoluminescence line scans of two thin film CdTe based solar cells und...Fig. 78 a,c) Experimental and simulated electroluminescence images of 6 × 4 mm² ...Fig. 79 The scanning tunneling microscopy map of a thin film CdTe based solar sh...Fig. 80 Voltage mapping design with thin Cr electrode on the back wall of CdTe b...Fig. 81 Lock-in thermography maps of the same thin film CdTe based cell before (...Fig. 82 ‘Small’ and ‘large’ area (A) CdTe based cells (left) grown under identic...Fig. 83 The distributions of fill factors (FF) of a database of about 100 CdTe b...Fig. 84 The statistical distributions of CIGS module efficiencies, and open circ...Fig. 85 The statistical distribution of the open-circuit voltages of ~ 1 cm size...Fig. 86 The electroluminescence maps of two PV modules showing the cell connecti...Fig. 87 The measured variations between voltages of individual cells constitutin...Fig. 88 A sketch of the self-healing mechanism of the weak diodes and shunts tre...Fig. 89 High resistive electrode mapping of a 10x10 cm² cell before and after th...Fig. 90 The current voltage characteristics of the untreated (no IFL) CdTe based...Fig. 91 Cell performance parameters [37] as a function of CdTe thickness for cel...

4 Part IVFig. 92 (a) SEM cross section image of a CdTe/CdS/TCO based junction. Courtesy R...Fig. 93 (a) A sketch of the microscopic structure of amorphous hydrogenated sili...Fig. 94 (a) Energy levels of localized states in the mobility gap filled with pa...Fig. 95 (a) Local fluctuation in the concentration of localized charges (circled...Fig. 96 Side and top views of structural elements and electric charge distributi...Fig. 97 Sketch of the random potential fluctuations in arbitrary lateral directi...Fig. 98 Band diagrams of some structures with “electrode” screening: (a) p-i-n d...Fig. 99 (a) A potential barrier for holes formed by the charged grain boundary s...Fig. 100 The transport pathway for electrons is dominated by the maximum barrier...Fig. 101 Percolation cluster for large samples with dimensions L significantly e...Fig. 102 Left: Different conductive pathways for transversal electronic transpor...Fig. 103 (a) Staircase of energy levels forming a recombination channel is a sys...Fig. 104 The probabilistic distribution of recombination channels times. A shado...Fig. 105 The tilted staircase recombination/hopping channel across a noncrystall...Fig. 106 p-n junction under reverse bias. Optimal chain hopping occurs through a...Fig. 107 Statistics of nonideality factors for poor and better performing cells.Fig. 108 A sketch of CdS structure unit.Fig. 109 A sketch of ionic displacements leading to piezo effect in CdS structur...Fig. 110 Surface charges and built-in electric field in response to the hydrosta...Fig. 111 (a) A sketch of the electric potential ϕ distribution along a CdS junct...Fig. 112 Squeezing experiments with pressure perpendicular to the face of thin-f...Fig. 113 Left: Bending experiments with glass superstrates for applying stress p...Fig. 114 The typical reversible pressure-induced evolution of the current-voltag...Fig. 115 Open-circuit voltage (V_oc) and short circuit current (J_sc) of the CdTe/...Fig. 116 Kelvin probe mapped microscopic local potential variations parallel to ...Fig. 117 Kelvin probe mapped microscopic local potential variations parallel to ...

5 Part VFig. 118 The two-diode model.Fig. 119 A simplified thin film geometry of two neighboring areas in a thin film...Fig. 120 Left: A one-dimensional finite element representation of the distribute...Fig. 121 Numerical modeling of a runaway instability in a system of two diodes u...Fig. 122 Schematic of the cell used in our experiments; not to scale. Dark strip...Fig. 123 The typical current voltage and power voltage characteristics of the st...Fig. 124 IR mapping of a PV module showing the hot spot development and its temp...Fig. 125 The evolution of temperature distribution in a 10x10 cm² region close t...Fig. 126 Temporal variations of voltage on the power source (V_PS), voltage in th...Fig. 127 Left, physical grid and TCO structure divided into nodes. Grey lines re...Fig. 128 Left, node containing grid and TCO. Upper right, geometry for determini...Fig. 129 The equivalent circuit of a node showing TCO/grid structure on top, and...Fig. 130 Simulated temperature distributions at different time instances. Note t...Fig. 131 Simulated and experimental temporal dependencies of temperature at the ...Fig. 132 Simulated and experimental temporal dependencies of voltages at the hot...Fig. 133 Initial voltage distribution along the length of the cell, on and off t...Fig. 134 Initial heat generation within the cell. Represented with permission fr...Fig. 135 Simulated temporal temperature dependencies as a function of substrate ...Fig. 136 Sketches of temperature and electric potential distributions across the...

6 Part VIFig. 137 Left: A representative relative degradation of efficiency of a CdTe bas...Fig. 138 Examples of PV parameter degradation for CdTe based cells [5].Fig. 139 Degradation of the maximum power point voltage (Vmpp) and power at the ...Fig. 140 Left and right: untypical degradation behavior of two CdTe based solar ...Fig. 141 Correlation between the degradation of efficiency (percent) between two...Fig. 142 Left: Correlation between the relative degradation of efficiency during...Fig. 143 The histogram of the relative efficiency degradation of about 1000 CdTe...Fig. 144 Degradation of CdTe based solar cells under different bias conditions: ...Fig. 145 The CdTe based dot cell configurations corresponding to the three stage...Fig. 146 Left: Relative open circuit voltage in the light and dark halves of the...Fig. 147 Histogram of reported degradation rates for Si crystalline PV (left), a...Fig. 148 Chart of affected modules scaled by the severity for thin-film modules....Fig. 149 Left: Log-normal distribution of the shunt resistance in an unstressed ...Fig. 150 Sketches of some thin film PV specific instabilities. (a) Dielectric br...Fig. 151 (a) Themporal variations of the AFM current in the conductive mode with...Fig. 152 EBIC amplitude temporal decay for CdTe based thin film PV cells of thre...Fig. 153 Comparison of the degradation data with fitting dependence of Eq. (175)...Fig. 154 The integral photoluminescence (PL) intensity shows temporal decay that...Fig. 155 The rescaled temporal decay curves for temporal decay due to continuous...Fig. 156 A sketch of statistical distributions in PV efficiency (Eff) varying in...

7 AppendixFig 1. The simplest diode model (a) of a built-in uniform field and imaginary cr...