At an elevated temperature of 90 °C, a chemical bath deposition using an aqueous solution of Zn(NO₃)₂·6H₂O and (CH₂)₆N₄ resulted in the formation of both nanoflowers and microrods of ZnO on F-doped SnO₂ glass with a seed layer. The nanoflowers and microrods were sensitized with dyes for application to the photoelectrodes of dye-sensitized solar cells (DSSCs). By extending the growth time of ZnO, the formation of nanoflowers was reduced and the formation of microrods favored. As the growth time was increased from 4 to 6 and then to 8 h, the open circuit voltage (V_oc) values of the DSSCs were increased, whilst the short circuit current (J_sc) values varied only slightly. Changes in the dye-loading amount, dark current, and electrochemical impedance were monitored and they revealed that the increase in V_oc was found to be due to a retardation of the charge recombination between photoinjected electrons and I₃⁻ ions and resulted from a reduction in the surface area of ZnO microrods. A reduced surface area decreased the dye contents adsorbed on the ZnO microrods, and thereby decreased the light harvesting efficiency (LHE). An increase in the electron collection efficiency attributed to the suppressed charge recombination counteracted the decreased LHE, resulting in comparable J_sc values regardless of the growth time.

By simple soaking titanium dioxide (TiO₂) films in an aqueous Na₂S solution, we could prepare surface-modified photoanodes for application to dye-sensitized solar cells (DSSCs). An improvement in both the open-circuit voltage (V_oc) and the fill factor (FF) was observed in the DSSC with the 5 min-soaked photoanode, compared with those of the control cell without any modification. The UV–visible absorbance spectra, UPS valence band spectra, and dark current measurements revealed that the Na₂S modification led to the formation of anions on the TiO₂ surface, and thereby shifted the conduction band edge of TiO₂ in the negative (upward) direction, inducing an increase of 29 mV in the V_oc. It was also found that the increased FF value in the surface-treated device was attributed to an elevation in the shunt resistance.

The efficiency of thin-film chalcogenide solar cells is dependent on their window layer thickness. However, the application of an ultrathin window layer is difficult because of the limited capability of the deposition process. This paper reports the use of atomic layer deposition (ALD) processes for fabrication of thin window layers for Cu(In_x,Ga_1−x)Se₂ (CIGS) thin-film solar cells, replacing conventional sputtering techniques. We fabricated a viable ultrathin 12 nm window layer on a CdS buffer layer from the uniform conformal coating provided by ALD. CIGS solar cells with an ALD ZnO window layer exhibited superior photovoltaic performances to those of cells with a sputtered intrinsic ZnO (i-ZnO) window layer. The short-circuit current of the former solar cells improved with the reduction in light loss caused by using a thinner ZnO window layer with a wider band gap. Ultrathin uniform A-ZnO window layers also proved more effective than sputtered i-ZnO layers at improving the open-circuit voltage of the CIGS solar cells, because of the additional buffering effect caused by their semiconducting nature. In addition, because of the precise control of the material structure provided by ALD, CIGS solar cells with A-ZnO window layers exhibited a narrow deviation of photovoltaic properties, advantageous for large-scale mass production purposes.

Bifacial CuInSe₂ (CISe) solar cells hold significant promise for various applications but are constrained by relatively low power conversion efficiencies. This study boosts performance through reducing CISe absorber deposition temperature and using low‐Ga back grading for an optimum gallium‐to‐indium ratio (Ga/(Ga+In); GGI) profile. Low deposition temperatures reduced ITO back contact thermal degradation, while low Ga concentration reduced GaO_X formation and CISe/ITO charge recombination. Ag incorporation significantly improved key photovoltaic parameters, including open‐circuit voltage (V_OC) and fill factor (FF), while reducing Cu_2−XSe secondary phase formation. This approach enables high‐quality CISe growth below 420 °C‐substantially lower than conventional temperatures. The study achieves record efficiency in the narrow bandgap CISe category, with Ag‐alloyed devices demonstrating a champion rear‐side efficiency of 8.44% at 390 °C, and a front‐side efficiency of 15.30% at 420 °C. Under the assumption of double‐sided total 2.0 solar illumination in an albedo environment, a champion bifacial power generation density (BPGD) of 23.1 mWcm⁻² is achieved. Results indicate that lower deposition temperatures enhance rear‐side performance, highlighting the role of low‐temperature processing, low Ga doping, and Ag alloying in suppressing carrier recombination losses in CISe solar cells.

Silver (Ag) incorporation has proven to be an effective approach for enhancing photovoltaic energy generation by tailoring the properties of chalcogenide absorbers. In thin‐film photovoltaic technology, inorganic solar cells such as Cu(In,Ga)(S,Se) ₂ , Cu ₂ ZnSn(S,Se) ₄ , Sb ₂ (S,Se) _3, and other chalcogenide thin‐film absorbers offer significant potential due to their tunable bandgaps, strong light absorption, and compatibility with scalable manufacturing processes. This review focuses on recent advancements in Ag incorporation within the chalcogenide family, emphasizing device principles, absorber suitability, and performance limitations. Both numerical and experimental studies demonstrate that Ag introduction promotes favorable growth orientations under controlled conditions while passivating defects and reducing recombination losses. The discussion concludes with strategies to overcome challenges associated with Ag incorporation. Finally, pathways for the practical application of Ag incorporation in chalcogenides for solar energy harvesting are discussed to enhance their efficiency.

Transparent rear contacts that combine efficient charge extraction with low optical loss are essential for extending Sb ₂ (S,Se) ₃ photovoltaics toward bifacial and tandem applications. Here, a solution‐processed 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (Spiro‐OMeTAD)/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) bilayer is introduced as a polymeric transparent rear‐contact architecture for bifacial Sb ₂ (S,Se) ₃ solar cells. Established dimethyl sulfoxide (DMSO) solvent engineering reduces the sheet resistance of PEDOT:PSS by nearly four orders of magnitude while preserving its high transparency, enabling front‐ and rear‐side power conversion efficiencies (PCEs) of 8.2% and 3.3%, respectively. Under 1‐sun front plus 0.3‐sun rear illumination, the bifacial device delivers a power generation density of 9.7 mW cm ⁻² . Combined optical and electrical analyses reveal that the lower rear‐side response arises from asymmetric photogeneration, direction‐dependent carrier transport, depth‐dependent absorber inhomogeneity, and enhanced recombination associated with the transparent rear interface. The device is further integrated as the top cell in an electrically independent Sb ₂ (S,Se) ₃ /CuInSe ₂ four‐terminal tandem, achieving a combined standard‐condition PCE of 12.32%. This work demonstrates a solution‐processable polymeric rear‐contact strategy complementary to conventional inorganic transparent contacts and identifies the optical and interfacial factors governing bifacial Sb ₂ (S,Se) ₃ photovoltaics.