# Light Harvesting and Optical-Electronic Properties of Two Quercitin and Rutin Natural Dyes  
[PERSON]  
1 College of Science, Northeast Forestry University, Harbin 150040, China; [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Q.L.) [PERSON]  
1 College of Science, Northeast Forestry University, Harbin 150040, China; [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Q.L.) [PERSON]  
1 College of Science, Northeast Forestry University, Harbin 150040, China; [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Q.L.) [PERSON]  
1 College of Science, Northeast Forestry University, Harbin 150040, China; [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Q.L.) [PERSON]  
2 School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China 22 School of  
relatively abundant. It can reduce the use of noble metals and has large absorption coefficients in the visible region [15], which has triggered much attention in the latest research in the field of DSSCs. The working mechanism of DSSCs includes five beneficial parts and some adverse reactions [16; 17]: (1) Upon molecules being excited by light, electrons simultaneously turn to the excited state. (2) The excited molecules are unstable, and then the electrons inject into the conduction band (CB) of TiO\({}_{2}\). (3) Electrons move from the photo anode to photo cathode. (4) Oxidation and reduction electrolytes get electrons from the counter electrode and make \(I_{3}^{-}\) change to \(I^{-}\). (5) Dyes in the excited state get electrons from the redox electrolyte, and thus return to the ground state. (6) Electrons in the (CB) of TiO\({}_{2}\) can be captured by excited molecules and the oxidation-reduction couples, and such a process can produce a dark current. The structures of DSSCs are mainly comprised of five parts: photon electrode, TiO\({}_{2}\), dyes, oxidation-reduction couples, and counter electrode. An external load lines the photon electrode and counter electrode [18; 19]. In 1991, DSSCs was first proposed by [PERSON] et al. [20], which opened a new door for the application of such a kind of new energy resource. Nowadays, several natural dyes, such as betalanins, carotenoids, anthocyanins, flavonoids, chlorophylls, and their co-pigments have been widely investigated [21; 22]. Recently, [PERSON] et al. [23], investigated the photoelectric properties of lawsonia inermis leaves that were extracted in cold ethanol (A) and soxhlet ethanol extractor (B) as natural sensitizers in DSSCs. The results showed that (A) achieved a \(\mathrm{J_{SC}}\) of 0.82 mA\(\cdot\)cm\({}^{-2}\), \(\mathrm{V_{OC}}\) of 0.302 V, f of 0.659, and \(\eta\) of 0.349%, and that of (B) were \(\mathrm{J_{SC}}\) of 0.94 mA\(\cdot\)cm\({}^{-2}\), \(\mathrm{V_{OC}}\) of 0.72 V, fill factor (ff) of 0.828, and \(\eta\) of 0.677%. [PERSON] et al. investigated the photoelectric properties of anthocyanins that were extracted from the petals of Caesalpinia pulcherrima in several different solvents [24]. The results showed that natural DSSCs that were based on citric acid solvents presented a higher efficiency of 0.83%. Natural dyes that were extracted from Murraya Koenigii Fruit (MKF), Hibiscus Sabdarifa Flower (HSF), and their mixtures at the rate of 1:1 were studied to illustrate the influence of functional groups on the optical and electrochemical performances of dyes by [PERSON] et al. [25]. It was found that the cocktail dyes showed dominant performance and had a higher voltage of 267 mV than individual MKF and HSF. The theoretical calculation can offer actual guidance and illustrate the close connection between the configurations and performances of dyes [26; 27; 28; 29; 30]. The parameters of fluorescence emission and charge collection efficiencies (which have a close relationship with the event of photo-to-electric conversion efficiency) have been calculated by [PERSON] et al. [28] through density functional theory/time dependent (DFT/TD)-DFT methods. The results offered a method for predicting the photovoltaic activities of molecules and provided guidance for the experimental synthesis of DSSCs.