JPH0235472B2 - - Google Patents
Info
- Publication number
- JPH0235472B2 JPH0235472B2 JP56085244A JP8524481A JPH0235472B2 JP H0235472 B2 JPH0235472 B2 JP H0235472B2 JP 56085244 A JP56085244 A JP 56085244A JP 8524481 A JP8524481 A JP 8524481A JP H0235472 B2 JPH0235472 B2 JP H0235472B2
- Authority
- JP
- Japan
- Prior art keywords
- semiconductor layer
- type semiconductor
- layer
- photovoltaic device
- junction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F10/00—Individual photovoltaic cells, e.g. solar cells
- H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
- H10F10/17—Photovoltaic cells having only PIN junction potential barriers
- H10F10/172—Photovoltaic cells having only PIN junction potential barriers comprising multiple PIN junctions, e.g. tandem cells
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/548—Amorphous silicon PV cells
Landscapes
- Photovoltaic Devices (AREA)
Description
【発明の詳細な説明】
この発明は光エネルギーを電気エネルギーに効
率よく変換することができる光発電素子に関する
ものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photovoltaic device that can efficiently convert light energy into electrical energy.
従来、半導体の光起電力効果を利用して光から
電気を発生する光発電素子としてはSi、GaAs、
CdSおよびアモルフアスSiなどの単一素材で構成
する単一接合構造と、異なつた素材を組合せた例
えばタンデム構造、カスケード接続構造、スタツ
クド接続構造などの多接合（異種多接合）構造が
提案されている。すなわち、第１図は従来の単一
接合構造の光発電素子を示す断面構造図である。
同図において、１はステンレス基板、２はこのス
テンレス基板１上に形成したn+−型半導体層、
３はこのn+−型半導体層２上に形成し、真性の
前記半導体層よりバンド間隙の狭いｉ−型半導体
層、４はこのｉ−型半導体層３上に形成したｐ−
型半導体層、５はこのｐ−型半導体層４上に形成
した透明電極、６は金属グリツド電極である。 Conventionally, photovoltaic elements that generate electricity from light using the photovoltaic effect of semiconductors include Si, GaAs,
Single-junction structures made of a single material such as CdS and amorphous Si, and multi-junction (heterogeneous multi-junction) structures such as tandem structures, cascade connection structures, and stacked connection structures that combine different materials have been proposed. . That is, FIG. 1 is a cross-sectional structural diagram showing a conventional single-junction structure photovoltaic device.
In the figure, 1 is a stainless steel substrate, 2 is an n + − type semiconductor layer formed on this stainless steel substrate 1,
3 is an i-type semiconductor layer formed on this n + -type semiconductor layer 2 and has a narrower band gap than the intrinsic semiconductor layer, and 4 is a p-type semiconductor layer formed on this i-type semiconductor layer 3.
5 is a transparent electrode formed on the p-type semiconductor layer 4, and 6 is a metal grid electrode.
この単一接合構造の光発電素子による太陽光エ
ネルギー変換効率は禁制帯幅1.5eV近辺で最大効
率が得られる。そして、更に高効率を得るために
は太陽光の全スペクトルに亘つて高い感度を有す
る異種接合構造の光発電素子が利用される。第２
図は従来の異種多接合構造の光発電素子を示す断
面構造図であり、一例としてタンデム構造を示
す。同図において、２ａはｐ−型半導体層４上に
形成したn+−型半導体層、３ａはこのn+−型半
導体層２ａ上に形成し、真性の前記半導体層より
バンド間隙の狭いｉ−型半導体層、４ａはこのｉ
−型半導体層３ａ上に形成したｐ−型半導体層で
ある。 The maximum solar energy conversion efficiency of this single-junction photovoltaic device is achieved at a forbidden band width of around 1.5 eV. In order to obtain even higher efficiency, a photovoltaic element with a heterojunction structure that has high sensitivity over the entire spectrum of sunlight is used. Second
The figure is a cross-sectional structural diagram showing a conventional photovoltaic device having a heterogeneous multi-junction structure, and shows a tandem structure as an example. In the figure, 2a is an n + -type semiconductor layer formed on the p-type semiconductor layer 4, 3a is an i-type semiconductor layer formed on this n + -type semiconductor layer 2a, and has a narrower band gap than the intrinsic semiconductor layer. type semiconductor layer, 4a is this i
This is a p- type semiconductor layer formed on the - type semiconductor layer 3a.
この構成による光発電素子の異種多接合は
pnpn…の接続であり、中央のpn接続の一部分に
p+n+領域を設けたトンネル接続あるいは金属電
極接続が用いられている。この異種多接合構造で
は電気エネルギーに変換されない損失として、(イ)
中央部分のトンネル接続または金属電極接続部分
での光吸収分は半導体への光の到達量を減少させ
る。(ロ)Ｐ−型半導体層４、ｉ−型半導体層３、及
びｎ−型半導体層２からなる第１層と、Ｐ−型半
導体層４ａ、ｉ−型半導体層３ａ、及びｎ−型半
導体層２ａからなる第２層との間に流れる光電流
の大きさは、第１層のＰ−型半導体層４における
正孔と、第２層のｎ−型半導体層２ａにおける電
子とが再結合する量によつて決まるから、構造設
計上の制約によつて、Ｐ−型半導体層４における
正孔の量とｎ−型半導体層２ａにおける電子の量
との間にアンバランスが生じた場合には、再結合
できずに余つてしまつた分の電子または正孔が無
駄な損失となる。等があり、これらの損失によつ
て変換効率が悪くなるという欠点があつた。 The heterogeneous multi-junction of the photovoltaic device with this configuration is
pnpn... connection, part of the central pn connection
Tunnel connections with p + n + regions or metal electrode connections are used. In this heterogeneous multi-junction structure, (a)
Light absorption at the tunnel connection or metal electrode connection portion in the central portion reduces the amount of light reaching the semiconductor. (b) A first layer consisting of a P-type semiconductor layer 4, an i-type semiconductor layer 3, and an n-type semiconductor layer 2, a P-type semiconductor layer 4a, an i-type semiconductor layer 3a, and an n-type semiconductor The magnitude of the photocurrent flowing between the second layer 2a and the second layer 2a is determined by the recombination of holes in the first P-type semiconductor layer 4 and electrons in the second N-type semiconductor layer 2a. Therefore, if an imbalance occurs between the amount of holes in the P-type semiconductor layer 4 and the amount of electrons in the N-type semiconductor layer 2a due to constraints on the structural design, The surplus electrons or holes that cannot be recombined are wasted losses. These losses have the disadvantage of deteriorating conversion efficiency.
したがつて、この発明の目的は光エネルギーの
電気エネルギーに変換されない損失、特に第１層
で発生する正孔の量と、第２層で発生する電子の
量とを同一にしなければならないことからくる構
造設計上の制約による損失を極めて少なくするこ
とができる光発電素子を提供するものである。 Therefore, the purpose of this invention is to eliminate the loss of optical energy that is not converted into electrical energy, especially since the amount of holes generated in the first layer must be equal to the amount of electrons generated in the second layer. The present invention provides a photovoltaic element that can extremely reduce losses due to structural design constraints.
このような目的を達成するため、この発明は
npn構造を形成する第１層および第２層の２種の
禁制帯幅（あるいは光学的選移間隔）を備えた異
種多接合構造の光発電素子であり、以下実施例を
用いて詳細に説明する。 In order to achieve this purpose, this invention
It is a photovoltaic device with a heterogeneous multi-junction structure having two kinds of forbidden band widths (or optical transition distances) in the first layer and the second layer forming an npn structure, and will be explained in detail below using examples. do.
第３図はこの発明に係る光発電素子の一実施例
を示す断面構造図であり、nipin／基板構造であ
る。同図において、３ｂはｐ−型半導体層４上に
形成し、真性の前記半導体層よりバンド間隙の狭
いｉ−型半導体層、２ｂはこのｉ−型半導体層３
ｂ上に形成したn+−型半導体層である。 FIG. 3 is a cross-sectional structural diagram showing an embodiment of the photovoltaic device according to the present invention, and is a nipin/substrate structure. In the figure, 3b is an i-type semiconductor layer formed on the p-type semiconductor layer 4 and has a narrower band gap than the intrinsic semiconductor layer, and 2b is this i-type semiconductor layer 3.
This is an n + -type semiconductor layer formed on b.
なお、この光発電素子の端部で、ｐ−型半導体
層４から第４図に示すように別の電極端子７を設
けることはもちろんである。 It goes without saying that at the end of this photovoltaic element, another electrode terminal 7 is provided from the p-type semiconductor layer 4 as shown in FIG.
次に、この構成による異種多接合構造の光発電
素子では第１層および第２層のｐ−ｉ−ｎ接合構
造を独立に最適設計できる。すなわち、従来は第
１層及び第２層からなるPin型の２つの光発電素
子を直列に接続しており、この第１層と第２層と
の間を流れる電流の大きさは、Ｐ−型半導体層４
の正孔とｎ−型半導体層２ａの電子との再結合の
量に依存するから、光電変換効率を最も良くする
ためには第１層で発生する光電流と第２層で発生
する光電流の大きさを合わせる必要があるのに対
し、第３図に示す構成ではｎ−型半導体層２、ｉ
−型半導体層３、及びＰ−型半導体層４からなる
第１層と、ｎ−型半導体層２ｂ、ｉ−型半導体層
３ｂ、及びＰ−型半導体層４からなる第２層とか
らなるPin型の２つの光発電素子を、Ｐ−型半導
体層４を共通の正電極として並列に接続している
から、第１層で発生する光電流と第２層で発生す
る光電流の大きさを合わせなくても、それぞれの
層（セル）の電力を独立に取り出せるため、設計
上の任意性が増し、設計の余裕度が大きくなり、
第１層、第２層の半導体の物性常数による最適構
造を選ぶことができる。この第１層の半導体とし
てはできるだけ禁制帯幅Eg1を大きくして短波長
光に対して損失を少なく電気に変換させる材料、
例えば1.6〜1.8eVを選ぶ。この1.6〜1.8eVは地上
太陽光スペクトルの第１の短波長ピークを吸収す
るのに必要であり、かつエネルギー損失を少なく
するような値としたものである。また、第２層の
半導体としてはEg1以下のエネルギーの光をよく
吸収し、かつエネルギー損失の少ないことを考慮
すると、1.0eV近傍の半導体がよい。したがつ
て、第１層はEg1以下に対してはほとんど吸収が
なく、Eg1以上に対しては有効な吸収と光発生電
流寄与を行なうのに十分な層厚さとし、第２層は
膜質から許されるかぎり厚い膜として光を有効に
利用するようにする。このとき、発生光電流の極
限値は太陽光スペクトル分布と半導体のバンドギ
ヤツプ（禁制帯幅）から理論的に予測できる。 Next, in the photovoltaic device having a heterogeneous multi-junction structure with this configuration, the pin junction structures of the first layer and the second layer can be optimally designed independently. That is, conventionally, two pin-type photovoltaic elements consisting of a first layer and a second layer are connected in series, and the magnitude of the current flowing between the first layer and the second layer is P- type semiconductor layer 4
Since it depends on the amount of recombination between the holes in the n-type semiconductor layer 2a and the electrons in the n-type semiconductor layer 2a, in order to maximize the photoelectric conversion efficiency, the photocurrent generated in the first layer and the photocurrent generated in the second layer are It is necessary to match the size of the n-type semiconductor layer 2, i
Pin consists of a first layer consisting of a − type semiconductor layer 3 and a P− type semiconductor layer 4, and a second layer consisting of an n− type semiconductor layer 2b, an i− type semiconductor layer 3b, and a P− type semiconductor layer 4. Since two type photovoltaic elements are connected in parallel with the P-type semiconductor layer 4 as a common positive electrode, the magnitude of the photocurrent generated in the first layer and the photocurrent generated in the second layer can be Since power can be extracted from each layer (cell) independently without having to match them, design flexibility is increased, and design margin is increased.
The optimum structure can be selected based on the physical property constants of the semiconductors of the first layer and the second layer. This first layer semiconductor is made of a material that increases the forbidden band width Eg 1 as much as possible and converts short wavelength light into electricity with less loss.
For example, choose 1.6 to 1.8 eV. This 1.6 to 1.8 eV is necessary to absorb the first short wavelength peak of the terrestrial sunlight spectrum, and is set to a value that reduces energy loss. Further, as the second layer semiconductor, a semiconductor with an energy of around 1.0 eV is preferable, considering that it absorbs light with an energy of Eg 1 or less well and has little energy loss. Therefore, the first layer should have almost no absorption for Eg 1 or less, and be thick enough to provide effective absorption and photogenerated current contribution for Eg 1 or more, and the second layer should have a film quality. The aim is to make effective use of light as a film that is as thick as possible. At this time, the limit value of the generated photocurrent can be theoretically predicted from the sunlight spectral distribution and the bandgap of the semiconductor.
なお、以上の実施例で使用する半導体としては
禁制帯幅が前記した制限に合致するものであれば
どのような材料であつてもよいことはもちろんで
ある。したがつて、アモルフアス・シリコンおよ
びその他のアモルフアス半導体（ａ−SiGe、ａ
−As、ａ−Ｂ、ａ−Ｃ、ａ−SiCなど）を用いて
もよいことはもちろんである。 It goes without saying that the semiconductor used in the above embodiments may be any material as long as the forbidden band width meets the above-described restrictions. Therefore, amorphous silicon and other amorphous semiconductors (a-SiGe, a
-As, a-B, a-C, a-SiC, etc.) may of course be used.
以上、詳細に説明したように、この発明に係る
光発電素子によれば第１層および第２層のPN接
合での電流を同一にしなければならないことから
くる構造設計上の制約による損失をきわめて少な
くすることができるから、理論的には40〜60％の
効率を期待することができる効果がある。 As explained above in detail, the photovoltaic device according to the present invention can minimize losses due to structural design constraints due to the fact that the currents in the PN junctions of the first and second layers must be the same. Since it is possible to reduce the amount of water used, it is theoretically possible to expect an efficiency of 40 to 60%.
第１図は従来の単一接合構造の光発電素子を示
す断面構造図、第２図は従来の異種多接合構造の
光発電素子を示す断面構造図、第３図および第４
図はこの発明に係る光発電素子の一実施例を示す
断面構造図である。
１……ステンレス基板、２，２ａおよび２ｂ…
…n+−型半導体層、３，３ａおよび３ｂ……ｉ
−型半導体層、４および４ａ……ｐ型半導体層、
５……透明電極、６……金属グリツド電極。な
お、同一符号は同一または相当部分を示す。
Fig. 1 is a cross-sectional structural diagram showing a conventional single-junction structure photovoltaic device, Fig. 2 is a cross-sectional structural diagram showing a conventional heterogeneous multi-junction structure photovoltaic device, and Figs.
The figure is a cross-sectional structural diagram showing one embodiment of a photovoltaic device according to the present invention. 1... Stainless steel substrate, 2, 2a and 2b...
...n + -type semiconductor layer, 3, 3a and 3b...i
- type semiconductor layer, 4 and 4a...p type semiconductor layer,
5...Transparent electrode, 6...Metal grid electrode. Note that the same reference numerals indicate the same or equivalent parts.
Claims (1)
第１の半導体層上に、第１の半導体層より禁制帯
幅の狭い第１の真性半導体層を介して積層した第
１の半導体層とは逆の第２導電型を有する第２の
半導体層と、この第２の半導体層上に、第２の半
導体層より禁制帯幅の狭い第２の真性半導体層を
介して積層した第１導電型を有する第３の半導体
層と、上記第１乃至第３の半導体層とそれぞれ電
気的に接続された電極とを備えたことを特徴とす
る光発電素子。1 A first semiconductor layer having a first conductivity type, and a first semiconductor layer laminated on the first semiconductor layer via a first intrinsic semiconductor layer having a narrower band gap than the first semiconductor layer. a second semiconductor layer having a second conductivity type opposite to that of the second semiconductor layer; A photovoltaic device comprising: a third semiconductor layer having a conductivity type; and electrodes electrically connected to each of the first to third semiconductor layers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56085244A JPS57199272A (en) | 1981-06-01 | 1981-06-01 | Photogenerating elements |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56085244A JPS57199272A (en) | 1981-06-01 | 1981-06-01 | Photogenerating elements |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57199272A JPS57199272A (en) | 1982-12-07 |
| JPH0235472B2 true JPH0235472B2 (en) | 1990-08-10 |
Family
ID=13853144
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56085244A Granted JPS57199272A (en) | 1981-06-01 | 1981-06-01 | Photogenerating elements |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57199272A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0752268B2 (en) * | 1990-06-21 | 1995-06-05 | シャープ株式会社 | Optical writing type liquid crystal element |
| US5239189A (en) * | 1991-06-07 | 1993-08-24 | Eastman Kodak Company | Integrated light emitting and light detecting device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5626479A (en) * | 1979-08-13 | 1981-03-14 | Shunpei Yamazaki | Optoelectro conversion device |
-
1981
- 1981-06-01 JP JP56085244A patent/JPS57199272A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57199272A (en) | 1982-12-07 |
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