Global performance evaluation of solar cells using two models: from charge-transfer and recombination mechanisms to photoelectric properties

Abstract

We investigated the photoelectric properties of two indoline dyes (CA2 and CA3) with different conjugated length spacers, and the same cyanoacrylic acid acceptor, and global evaluation models were developed based on the experimental results, the developed normal model, the transient spectrum results, and the theoretical normal model. First, the properties of two dyes were studied through ultraviolet-visible spectroscopy, energy levels, and molecular descriptors. The observations agreed well with calculations carried out through basis-set correction. Second, the short-circuit current density (J_sc) and open-circuit voltage (V_oc) curve were estimated by using the developed normal model (DNM) based on the transient spectrum, molar extinction coefficient, adsorption capacity, and recombination rate. The values of the DNM method (J_sc = 16.24 mA cm⁻², V_oc = 0.59 V, η% = 7.81 for CA2) were closer to the experimental results (J_sc = 17.27 mA cm⁻², V_oc = 0.59 V, η% = 6.57) compared with the normal model (J_sc = 21.66 mA cm⁻², V_oc = 0.50 V and η% = 8.67), which was evaluated by using the electron-injection lifetime, excited-state lifetime, fluorescence lifetime, energy difference between the TiO₂ conduction band (E_CBE), and the electron difference between the donor and the recipient (n_c) for J_sc and V_oc. The DNM could be used to evaluate J_sc, V_oc, and η from considerations of the relationship between the macroscopic properties and microscopic parameters, and provided an effective method to improve the molecular design and performance tuning by decreasing factors that affect the energy conversion unfavorably.