Physics of Thin-Film Photovoltaics. Victor G. Karpov

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