Progress and Perspectives of Thin Film Kesterite Photovoltaic Technology: A Critical Review

Abstract

The latest progress and future perspectives of thin film photovoltaic kesterite technology are reviewed herein. Kesterite is currently the most promising emerging fully inorganic thin film photovoltaic technology based on critical raw-material-free and sustainable solutions. The positioning of kesterites in the frame of the emerging inorganic solar cells is first addressed, and the recent history of this family of materials briefly described. A review of the fast progress achieved earlier this decade is presented, toward the relative slowdown in the recent years partly explained by the large opencircuit voltage (V OC ) deficit recurrently observed even in the best solar cell devices in the literature. Then, through a comparison with the close cousin Cu(In,Ga)Se 2 technology, doping and alloying strategies are proposed as critical for enhancing the conversion efficiency of kesterite. In the second section herein, intrinsic and extrinsic doping, as well as alloying strategies are reviewed, presenting the most relevant and recent results, and proposing possible pathways for future implementation. In the last section, a review on technological applications of kesterite is presented, going beyond conventional photovoltaic devices, and demonstrating their suitability as potential candidates in advanced tandem concepts, photocatalysis, thermoelectric, gas sensing, etc.Kesterite Photovoltaics He has supervised ten Ph.D. theses in the photovoltaic field. He is currently the coordinator of the research and innovation H2020 project STARCELL (www.starcell.eu), and the RISE (Marie Curie) project INFINITE-CELL (www.infinite-cell.eu).the V OC deficit for bandgaps close to 1.0 or 1.5 eV are comparable, and one can consider that kesterite is reasonably close to the state of the art of chalcopyrite materials in that range. But, while for kesterite the V OC deficit increases almost monotonically with the bandgap, it is markedly reduced for intermediate

Characterization of Surface and Heterointerface of Cu2ZnSn1–xGexSe4 for Solar Cell Applications

“…Ge‐incorporated Cu 2 Zn(Sn 1– x Ge x )Se 4 (CZTGSe) with kesterite crystal structure has attracted attention as a material for p‐type light absorbers in heterojunction solar cells . This is because the bandgap energy ( E g ) can be tuned from 1.0 to 1.4 eV by adjusting the cationic mixing ratios {Ge/(Ge + Sn) = x } from 0 to 1 .…”

“…Ge-incorporated Cu 2 Zn(Sn 1-x Ge x )Se 4 (CZTGSe) with kesterite crystal structure has attracted attention as a material for p-type light absorbers in heterojunction solar cells. [1][2][3][4][5][6][7][8][9][10][11][12] This is because the bandgap energy (E g ) can be tuned from 1.0 to 1.4 eV by adjusting the cationic mixing ratios {Ge/(Ge þ Sn) ¼ x} from 0 to 1. [7,[13][14][15][16] Using this material as a light absorber, the open circuit voltage (V OC ) loss can be improved compared with that of non-Ge-incorporated Cu 2 ZnSnSe 4 (CZTSe) (x ¼ 0) [7] and large grains of polycrystalline CZTGSe in the thin film.…”

Emerging inorganic solar cell efficiency tables (Version 1)

“…The understanding of dopant/alloying element induced changes particularly in the point defects and associated interface engineering would lead to further performance improvement. For a more complete review of the recent approaches of cation substitution in kesterites, readers may refer to the review article by Giraldo et al [55].…”

Physical routes for the synthesis of kesterite

“…The main objective of kesterite alloying is to enable the tuning of the properties of the material for advanced device engineering. It is also viewed as a possible solution for intrinsic problems of kesterite absorbers like the Cu/Zn disorder or Sn-multivalency [126]. The most interesting alloying elements for kesterites are Ag replacing Cu, Cd replacing Zn, and Ge replacing Sn for cationic substitution, as well as Se replacing S for anionic substitution [126].…”

“…It is also viewed as a possible solution for intrinsic problems of kesterite absorbers like the Cu/Zn disorder or Sn-multivalency [126]. The most interesting alloying elements for kesterites are Ag replacing Cu, Cd replacing Zn, and Ge replacing Sn for cationic substitution, as well as Se replacing S for anionic substitution [126]. In principle, the introduction of all these elements in the basic kesterite structure can be performed by the PVD techniques described above and the monograin powder technology.…”