实用光伏手册：原理与应用（原著第2版）（上）

《实用光伏手册：原理与应用（上）（原著第2版）（导读版）》主要讨论了太阳电池制造技术。首先介绍了太阳电池运行的物理学、材料和模型化以及基础理论框架；其次详细描述晶硅技术；然后分别介绍了薄膜太阳电池的所有方面、在空间和聚光系统中使用的高效率电池以及基于分子结构的器件等内容。

第2版序言
第1版序言
编者
引论
Part ⅠA:太阳电池
ⅠA-1.太阳电池工作原理 T.Markvart and L.Casta*er
1.引言
2.电学特征
3.光学特性
4.经典太阳电池结构
ⅠA-2.半导体材料和模型化 T.Markvart and L.Casta*er
1.引言
2.半导体能带结构
3.半导体中的载流子统计
4.输运方程
5.载流子迁移率
6.光吸收作用下的载流子增殖
7.复合
8.辐射损伤
9.重掺杂效应
10.氢化非晶硅的性能
感谢
ⅠA-3.理想效率 P.T.Landsberg and T.Markvart
1.引言
2.热力学效率
3.与能量相关的效率
4.使用肖特基太阳电池方程的效率
5.对效率的一般解释
Part ⅠB:晶硅太阳电池
ⅠB-1.晶硅:制造和性能 F.Ferrazza
1.引言
2.用于光伏制造的硅晶片的特征
3.原料硅
4.晶体制备方法
5.成形和硅片切割
ⅠB-2.高效率硅太阳电池概念 M.A.Green
1.引言
2.高效率实验室电池
3.丝网印刷电池
4.激光处理电池
5.HIT电池
6.背接触电池
7.总结
致谢
ⅠB-3.晶硅太阳电池的低成本工业化技术 J.Szlufcik,S.Sivoththaman,J.Nijs,R.P.Mertens and R.Van Overstraeten
1.引言
2.电池制程
3.工业太阳电池技术
4.商业光伏组件的成本
ⅠB-4.薄型硅太阳电池 M.Mauk,P.Sims,J.Rand and A.Barnett
1.引言、背景和评价
2.薄型硅太阳电池的光捕获
3.薄型硅太阳电池的电压增强
4.薄型太阳电池的硅沉积和晶体生长
5.基于基板减薄的薄型硅太阳电池
6.器件结果总结
Part ⅠC:薄膜技术
ⅠC-1.薄膜硅太阳电池 A.Shah
1.引言
2.氢化非晶硅(a-Si:H)层
3.氢化微晶硅(μc-Si:H)层
4.p-i-n和n-i-p结构的薄膜太阳电池的功能
5.串联和多结太阳电池
6.组件产品和性能
7.总结
ⅠC-2.CdTe薄膜光伏组件 D.Bonnet
1.引言
2.制备CdTe薄膜太阳电池的步骤
3.集成组件的制备
4.CdTe薄膜组件的生产
5.产品及其应用
6.未来展望
ⅠC-3.Cu(In,Ga)Se₂薄膜太阳电池 U.Ran and H.W.Schock
1.引言
2.材料性能
3.电池和组件技术
4.器件物理
5.宽带隙黄铜矿
6.结论
致谢
ⅠC-4.为光伏应用的黄铜矿化合物半导体研究进展和研究成果转化为实际的太阳电池产品 A.J?ger-Waldau
1.引言
2.研究方向
3.工业化
4.结论和展望
Part ⅠD:空间太阳电池和聚光电池
ⅠD-1.GaAs和高效率空间太阳电池 V.M.Andreev
1.Ⅲ-Ⅴ族太阳电池的历史回顾
2.单结Ⅲ-Ⅴ族空间太阳电池
3.多结空间太阳电池
致谢
ⅠD-2.高效率Ⅲ-Ⅴ族多结太阳电池 S.P.Philipps,F.Dimroth and A.W.Bett
1.引言
2.Ⅲ-Ⅴ族多结太阳电池的特殊方面
3.Ⅲ-Ⅴ族太阳电池概念
4.结论
致谢
ⅠD-3.单个太阳光高效率背接触硅太阳电池和聚光应用 P.J.Verlinden
1.引言
2.IBC太阳电池的聚光应用
3.背接触硅太阳电池
4.背接触太阳电池模型化
5.周边和边缘复合
6.背接触太阳电池的制备工艺
7.背接触太阳电池的稳定性
8.效率目标为30%的硅太阳电池
9.如何改善背接触太阳电池的效率
10.结论
致谢
Part ⅠE.染料敏化和有机太阳电池
ⅠE-1.染料敏化光电化学电池 A.Hagfeldt,U.B.Cappel,G.Boschloo,L.Sun,L.Kloo,H.Pettersson and E.A.Gibson
1.引言
2.光电化学电池
3.染料敏化太阳电池
4.未来展望
ⅠE-2.有机太阳电池 C.Dyer-Smith and J.Nelson
1.引言
2.有机电子材料
3.器件工作原理
4.太阳电池性能的优化
5.生产问题
6.结论

CHAPTER IA-1

Principles of Solar Cell Operation

Tom Markvarta and Luis Casta?erb

aSchool of Engineering Sciences, University of Southampton, UK

bUniversidad Politecnica de Catalunya, Barcelona, Spain

1. Introduction 7

2. Electrical Characteristics 10

2.1 The Ideal Solar Cell 10

2.2 Solar Cell Characteristics in Practice 13

2.3 The Quantum Efficiency and Spectral Response 15

3. Optical Properties 16

3.1 The Antireflection Coating 16

3.2 Light Trapping 17

4. Typical Solar Cell Structures 19

4.1 The pn Junction Solar Cell 19

4.1.1 The pn Junction 19

4.1.2 Uniform Emitter and Base 23

4.1.3 Diffused Emitter 23

4.2 Heterojunction Cells 25

4.3 The pin Structure 27

4.4 Series Resistance 29

References 30

1. INTRODUCTION

Photovoltaic energy conversion in solar cells consists of two essential

steps. First, absorption of light generates an electronhole pair. The electron

and hole are then separated by the structure of the device―electrons

to the negative terminal and holes to the positive terminal―thus generating

electrical power.

This process is illustrated in Figure 1, which shows the principal features of

the typical solar cells in use today. Each cell is depicted in two ways. One

diagram shows the physical structure of the device and the dominant electrontransport

processes that contribute to the energy-conversion process.

Figure 1 (a) The structure of crystalline silicon solar cell, the typical solar cell in use

today. The bulk of the cell is formed by a thick p-type base in which most of the incident

light is absorbed and most power is generated. After light absorption, the

minority carriers (electrons) diffuse to the junction where they are swept across by

the strong built-in electric field. The electrical power is collected by metal contacts

to the front and back of the cell (Chapters Ib-2 and Ib-3). (b) The typical

galliumarsenide solar cell has what is sometimes called a heteroface structure, by

virtue of the thin passivating GaAlAs layer that covers the top surface. The GaAlAs

‘window’ layer prevents minority carriers from the emitter (electrons) to reach the surface

and recombine but transmits most of the incident light into the emitter layer where

most of the power is generated. The operation of this pn junction solar cell is similar in

many respects to the operation of the crystalline silicon solar cell in (a), but the substantial

difference in thickness should be noted. (Chapters Id-1 and Id-2). (c) The structure

of a typical single-junction amorphous silicon solar cells. Based on pin junction, this

Figure 1 (Continued) cell contains a layer of intrinsic semiconductor that separates

two heavily doped p and n regions near the contacts. Generation of electrons and

holes occurs principally within the space-charge region, with the advantage that

charge separation can be assisted by the built-in electric field, thus enhancing the collection

efficiency. The contacts are usually formed by a transparent conducting oxide

(TCO) at the top of the cell and a metal contact at the back. Light-trapping features in

TCO can help reduce the thickness and reduce degradation. The thickness of a-Si solar

cells ranges typically from a fraction of a micrometer to several micrometers.

(Chapter Ic-1). (d), (e) The typical structures of solar cells based on compound semiconductors

copper indiumgallium diselenide (d) and cadmium telluride (e). The

front part of the junction is formed by a wide-band-gap material (CdS ‘window’) that

The same processes are shown on the band diagram of the semiconductor, or

energy levels in the molecular devices.

The diagrams in Figure 1 are schematic in nature, and a word of

warning is in place regarding the differences in scale: whilst the thickness

of crystalline silicon cells (shown in Figures 1(a) and 1(f)) is of the order

of 100 micrometres or more, the thickness of the various devices in

Figures 1(b)1(e) (thin-film and GaAs-based cells) might be several

micrometres or less. The top surface of the semiconductor structures

shown in Figure 1 would normally be covered with antireflection coating.

The figure caption can also be used to locate the specific chapter in this

book where full details for each type of device can be found.

2. ELECTRICAL CHARACTERISTICS

2.1 The Ideal Solar Cell

An ideal solar cell can be represented by a current source connected in parallel

with a rectifying diode, as shown in the equivalent circuit of Figure 2.

The corresponding IV characteristic is described by the Shockley solar

cell equation

I 5Iph 2Io e

qV

kBT 21 e1T

Figure 1 (Continued) transmits most of the incident light to the absorber layer (Cu(In,

Ga)Se2 or CdTe) where virtually all electronhole pairs are produced. The top contact is

formed by a transparent conducting oxide. These solar cells are typically a few micrometers

thick (Chapters Ic-2 and Ic-3). (f) Contacts can be arranged on the same side of

the solar cell, as in this point contact solar cell. The electronhole pairs are generated in

the bulk of this crystalline silicon cell, which is near intrinsic, usually slightly n-type.

Because this cell is slightly thinner than the usual crystalline silicon solar cell, efficient

light absorption is aided here by light trapping: a textured top surface and a reflecting

back surface (Chapter Ib-3). (g), (h) The most recent types of solar cell are based on

molecular materials. In these cells, light is absorbed by a dye molecule, transferring an

electron from the ground state to an excited state rather than from the valence band to

the conduction band as in the semiconductor cells. The electron is subsequently

removed to an electron acceptor and the electron deficiency (hole) in the ground state

is replenished from an electron donor. A number of choices exist for the electron acceptor

and donor. In the dye-sensitised cell (g, Chapter Ie-1), the electron donor is a redox

electrolyte and the role of electron acceptor is the conduction band of titanium dioxide.

In plastic solar cells (h, Chapter Ie-2), both electron donor and electron acceptor are

molecular materials.

Figure 2 The equivalent circuit of an ideal solar cell (full lines). Nonideal components

are shown by the dotted line.

where kB is the Boltzmann constant, T is the absolute temperature, q

(.0) is the electron charge, and V is the voltage at the terminals of the

cell. Io is well known to electronic device engineers as the diode saturation

current (see, for example, [1]), serving as a reminder that a solar cell

in the dark is simply a semiconductor current rectifier, or diode. The

photogenerated current Iph is closely related to the photon flux incident

on the cell, and its dependence on the wavelength of light is frequently

discussed in terms of the quantum efficiency or spectral response (see

Section 2.3). The photogenerated current is usually independent of the

applied voltage with possible exceptions in the case of a-Si and some

other thin-film materials [24].

Figure 3(a) shows the IV characteristic (Equation (1)). In the ideal

case, the short-circuit current Isc is equal to the photogenerated current

Iph, and the open-circuit voltage Voc is given by

Voc 5

kBT

q

ln 11

Iph

I0 e2T

The maximum theoretically achievable values of the short-circuit current

density Jph and of the open-circuit voltage for different materials are

discussed and compared with the best measured values in Chapter Ia-3.

The power P 5 IV produced by the cell is shown in Figure 3(b). The

cell generates the maximum power Pmax at a voltage Vm and current Im,

and it is convenient to define the fill factor FF by

FF 5

ImVm

IscVoc

5

Pmax

IscVoc e3T

The fill factor FF of a solar cell with the ideal characteristic (1) will be

furnished by the subscript 0. It cannot be determined analytically, but it

Figure 3 The IV characteristic of an ideal solar cell (a) and the power produced by

the cell (b). The power generated at the maximum power point is equal to the

shaded rectangle in (a).

can be shown that FF0 depends only on the ratio voc5Voc/kBT. FF0 is

determined, to an excellent accuracy, by the approximate expression [5]

FF0 5

voc 2lnevoc 10:72T

voc 11

The IV characteristics of an ideal solar cell complies with the superposition

principle: the functional dependence (1) can be obtained from the

corresponding characteristic of a diode in the dark by shifting the diode

characteristic along the current axis by Iph (Figure 4).