Solution Processed Cu₂CoSnS₄ Thin Films for Photovoltaic Applications

Abstract

Earth abundant alternative chalcopyrite Cu 2 CoSnS 4 (CCTS) thin films were deposited by a facile sol−gel process onto larger substrates. Temperature dependence of the process control of deposition and desired phase formations was studied in detail. Films were analyzed for complete transformation from amorphous to polycrystalline, with textured structures for stannite phase, as reflected from the X-ray diffraction and with nearly stoichiometric compositions of Cu:Co:Sn:S = 2:0:1:0:1:0:4:0 from EDAX analysis. Morphological investigations revealed that the CCTS films with larger grains, on the order of its thickness, were synthesized at higher temperature of 500 °C. The optimal band gap for application in photovoltaics was estimated to be 1.4 eV. Devices with SLG/CCTS/Al geometry were fabricated for real time demonstration of photoconductivity under A.M 1.5 G solar and 1064 nm infrared laser illuminations. A photodetector showed one order current amplification from ∼1.9 × 10 −6 A in the dark to 2.2 × 10 −5 A and 9.8 × 10 −6 A under A.M 1.5 G illumination and 50 mW cm −2 IR laser, respectively. Detector sensitivity, responsivity, external quantum efficiency, and gain were estimated as 4.2, 0.12 A/W, 14.74% and 14.77%, respectively, at 50 mW cm −2 laser illuminations. An ON and OFF ratio of 2.5 proved that CCTS can be considered as a potential absorber in low cost photovoltaics applications.

Defect Engineering in Multinary Earth‐Abundant Chalcogenide Photovoltaic Materials

“…121) . In addition to divalent Zn, the reported band gaps of Cu 2 ‐M II ‐Sn‐S 4 (M II = Mn, Fe, and Co) are also in the 1.2–1.5 eV range, spanning relevant values for single‐junction PV applications. However, these transition metals generally possess multiple charge‐states (e.g., the possible oxidation states of Mn are +7, +6, +5, +4, +3, +2, +1, −1, −2, −3), providing opportunity for the formation of harmful deep level defects.…”

Heat-up synthesis of Cu2SnS3 quantum dots for near infrared photodetection

“…The specic detectivity D* is the ability of a photodetector to detect the smallest light signal and is given by D* ¼ (ADf) 1/2 R l /i n , where A is the device area ¼ 0.1 mm 2 , Df is the frequency band width ¼ 3333. 33 Hz, R l is the responsivity and i n ¼ 11.9 pA is the value of the noise current obtained using noise measurements. 28 The calculated values of various parameters like responsivity, EQE and specic detectivity are shown in Table 1 for the IR lamp at different applied biases and in Tables 2 and 3 for 1550 nm and 1064 nm laser illuminations respectively at different intensities.…”

Solvothermal synthesis and tunable bandgap of Cu2(Zn1−xCox)SnS4 and Cu2(Fe1−xCox)SnS4 nanocrystals

“…Therefore, the effect of replacement of constituents in the quaternary chalcogenides by magnetic ions on their bandgap is worthwhile to be explored for applications in thermoelectric and photovoltaic devices. [23][24][25][26][27] respectively and thus are also the possible alternative for the absorber material of photovoltaic and thermoelectric devices. The ion radius of Co 2+ , 0.058 nm, is close to those of Zn 2+ , 0.060 nm, and Fe 2+ , 0.063 nm, and thus Co 2+ may incorporate into CZTS and CFTS to form the Cu 2 (Zn 1-x Co x )SnS 4 and Cu 2 (Fe 1-x Co x )SnS 4 alloys.…”