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Dong et al. Energy Mater. 2026, 6, 600026 Page 11 of 16

Figure 5. (A) J-V curves, (B) EQE spectra, (C) dark J-V curves, (D) dJ/dV vs. V graph for G extraction, (E) dV/dJ vs. (J + J SC - GV) graph for
-1
R and A extraction, and (F) ln(J + J SC - GV) vs. V-RJ graph for J0 extraction, for samples without and with NdCl 3 treatment.

Table 1. The photovoltaic parameters of Sb 2 Se 3 solar cells without and with NdCl 3 treatment

Sample V OC (V) J SC (mA/cm ) FF (%) Efficiency (%) R S (ohm) R SH (ohm)
2
W/O Nd 0.424 28.60 62.27 7.55 114.83 13,014
W Nd 0.465 30.54 64.58 9.17 110.48 19,782

Table 2. Electrical parameters related to the diode and interface for devices without and with NdCl 3 treatment

Sample G (mS/cm ) R (Ω cm ) A J0 (mA/cm ) W d (nm) N trap (cm )
2
2
-3
2
W/O Nd 4.93 × 10 -2 2.24 1.88 1.81 × 10 -3 216.44 2.98 × 10 14
W Nd 3.10 × 10 -3 2.173 1.52 9.42 × 10 -5 307.60 1.76 × 10 14
lower J 0, decreasing from 1.81 × 10 to 9.42 × 10 mA/cm . In principle, a lower J 0 suggests fewer shunt paths
2
-5
-3
and a reduced carrier recombination probability, indicating that Nd doping effectively mitigates the loss of
photogenerated carriers and favors higher V formation .
[50]
OC
To better understand the factors contributing to the differences in carrier lifetimes, capacitance-voltage
(C-V) analysis was also performed in this study. As shown in Figure 6A, the Mott-Schottky curves (1/C -V)
2
indicate that the built-in voltage of the W/O Nd device is 0.474 V, while that of the W Nd device is 0.530 V.
The increased built-in electric field provides a greater driving force for carrier separation, resulting in faster
charge separation . The parameters were calculated according to Supplementary Note 5 using the C-V
[51]
fitting method to extract the depletion width. The depletion widths (W ) of the W/O Nd and W Nd devices
d
were calculated to be 216.44 and 307.60 nm, respectively [Figure 6B]. A narrower depletion width indicates a
significant tunneling effect and insufficient carrier separation, which leads to a higher V deficit in the W/O
OC
Nd device . Figure 6C presents the EIS results for both devices. A similar circuit model was employed to
[52]
effectively fit the impedance results. Compared to the deposited samples, the R value of the device after
S