Solution-processed solar cells based on inorganic bulk heterojunctions with evident hole contribution to photocurrent generation

Abstract

To develop solution-processed and novel device structures is of great importance for achieving advanced and low-cost solar cells. In this paper, we report the solution-processed solar cells based on inorganic bulk heterojunctions (BHJs) featuring a bulk crystalline Sb2S3 absorbing layer interdigitated with a TiO2 nanoarray as an electron transporter. A solution-processed amorphous-to-crystalline transformation strategy is used for the preparation of Sb2S3/TiO2-BHJs. Steady-state and dynamic results demonstrate that the crystalline structure in the Sb2S3 absorbing layer is crucial for efficient devices, and a better Sb2S3 crystallization favors a higher device performance by increasing the charge collection efficiency for a higher short-circuit current, due to reduced interfacial and bulk charge recombinations, and enhancing the open-circuit voltage and fill factor with the reduced defect states in the Sb2S3 layer as well. Moreover, an evident contribution to photocurrent generation from the photogenerated holes in the Sb2S3 layer is revealed by experimental and simulated dynamic data. These results imply a kind of potential non-excitonic BHJ for energy conversion.

Preferentially oriented large antimony trisulfide single-crystalline cuboids grown on polycrystalline titania film for solar cells

“…400-nm-thick Sb 2 S 3 layer (i.e., n = 2) (Supplementary Table 4). With the diffusion coefficients (D) of 0.25 cm 2 s −1 for electrons 11 and 0.07 cm 2 s −1 for holes 17 and fill factor (FF) for 59.46% (Fig. 4c), for which a certified efficiency of η = 5.12 % was obtained from the National Institute of Metrology (NIM), China to confirm the reliability of the efficiency ( Supplementary Fig.…”

“…It should be noted that the efficiency of the present solar cell is not high enough yet. We envision that, for a better device performance, it is necessary to reduce the surface roughness of the Sb 2 S 3 layer, which may cause serious shorting risk 44 and charge recombination 11,45 to reduce V oc and FF values, to improve the charge collection efficiency in the device.…”

“…The solutionprocessing method, which mainly involves a film matrix formation by simple technologies (e.g., spin-coating, doctor blading, screen printing, injet printing) and a followed post-annealing at low temperatures (normally ≤ 500 o C), has been demonstrated to be an effective strategy to fabricate low-cost and efficient solar cells, for which a representative is hybrid perovskite solar cells that have reached the efficiency up to 22% 7,8 . However, the solutionprocessing methods for preparing the inorganic bulk p-type layers for efficient solar cells are still challenging 3 and rarely reported [9][10][11][12] .…”

Spin-coated planar Sb2S3 hybrid solar cells approaching 5% efficiency

“…The typical crystallization temperature is 300 °C [2,6,29,31,37] while values of 330 °C [4–5 32,50] and up to 400 °C [51] are reported. To gain insights into the crystallization behavior in terms of morphology, creation of defects and solar cell performance we produced samples crystallized on a hot plate at various temperatures in a nitrogen atmosphere.…”

“…4 and the position of the highest occupied molecular orbital (HOMO). The HOMO of Sb 2 S 3 obtained from ultraviolet photon spectroscopy (UPS) measurements is reported to lie between 5.3 and 5.5 eV [30,51,63] with one report claiming 5.9 eV [32]. Reported HOMO values of the polymers are 4.9–5.1 eV for P3HT [64–65] and 5.3–5.4 eV for KP115 [61,66] and are obtained from cyclic voltammetry measurements, which yields lower lying HOMO levels than UPS measurements [67].…”