Solar cell having light-absorbing structure

1. A solar cell comprising:

a first electrode;

a composite layer disposed on the first electrode and containing a porous metal oxide layer and a light absorber comprising an inorganic-organic hybrid perovskite compound;

a light-absorbing structure disposed on the composite layer and continuously extended from the light absorber of the composite layer, and consisting of a light absorber comprising an inorganic-organic hybrid perovskite compound which is same with the inorganic-organic hybrid perovskite compound of the light absorber of the composite layer;

a hole conductive layer disposed on the light-absorbing structure; and

a second electrode disposed on the hole conductive layer,

wherein the porous metal oxide layer of the composite layer includes aggregated metal oxide particles and pores between the metal oxide particles, and

the light absorber of the composite layer entirely fills in the pores of the porous metal oxide layer.

2. The solar cell of claim 1 , wherein the light-absorbing structure satisfies the following Correlation Equation 1:

0.05≤Cov/Surf≤1  (Correlation Equation 1)

(In Correlation Equation 1, Surf is the entire surface area of a surface of the composite layer on which the light-absorbing structure is disposed, and Cov is a surface area of the composite layer covered by the light-absorbing structure).

3. The solar cell of claim 1 , wherein Cov/Surf (Surf is the entire surface area of a surface of the composite layer on which the light-absorbing structure is disposed, and Cov is a surface area of the composite layer covered by the light-absorbing structure) corresponding to a surface coverage of the composite layer by the light-absorbing structure is 0.7 to 1.

4. The solar cell of claim 1 , wherein the light-absorbing structure includes a light absorber pillar, a light absorber thin film, or a light absorber pillar protruding on the light absorber thin film.

5. The solar cell of claim 4 , wherein the light absorber pillar has a column shape, a plate shape, a needle shape, a wire shape, a rod shape, or a mixed shape thereof.

6. The solar cell of claim 4 , wherein the light absorber thin film is a dense film, a porous film, or a laminate film thereof.

7. The solar cell of claim 1 , wherein the-light-absorbing structure includes a light absorber thin film having a thickness of 1 nm to 2000 nm.

8. The solar cell of claim 1 , wherein the inorganic-organic hybrid perovskite compounds of the light absorber of the composite layer and the light absorber of the light-absorbing structure are satisfying the following Chemical Formulas 1 and 2:

AMX3  (Chemical Formula 1)

(In Chemical Formula 1, A is a monovalent organic ammonium ion or Cs+, M is a divalent metal ion, and X is one or two or more halogen ions selected from Cl—, Br—, and I—), and

A2MX4  (Chemical Formula 2)

(In Chemical Formula 2, A is a monovalent organic ammonium ion or Cs+, M is a divalent metal ion, and X is one or two or more halogen ions selected from Cl—, Br—, and I—).

9. The solar cell of claim 1 , wherein the porous metal oxide layer has a thickness of 50 nm to 10 μm.

10. The solar cell of claim 1 , further comprising a metal oxide thin film disposed between the first electrode and the composite layer.

11. The solar cell of claim 1 , wherein the hole conductive layer is a monomer- or polymer-based organic hole transporting material.

12. The solar cell of claim 11 , wherein the organic hole transporting material is one or two or more selected from thiophene based hole conductive polymers, para-phenylene vinylene based hole transporting polymers, carbazole based hole transporting polymers, and triphenylamine based hole transporting polymers.