ORIGINAL PAPER Electrodeposited polyaniline/Cu 2 ZnSnSe 4 heterojunction Kazhmukhan Urazov 1 & Margarita Dergacheva 1 & Alexey Tameev 2 & Oxana Gribkova 2 & Konstantin Mit’ 3 Received: 18 September 2019 /Revised: 2 April 2020 /Accepted: 6 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract One-step method for the electrodeposition of thin Cu 2 ZnSnSe 4 (CZTSe) film onto a polyaniline/FTO/glass substrate was developed. Polyaniline film was preliminary obtained also by electrochemical deposition onto the FTO/glass substrate. The nucleation of CZTSe in the course of the film formation on the polyaniline surface was studied by chronoamperometry method. This process can be described by the instantaneous crystallization model. According to SEM data, the films consist of 25–50 nm nanocrystals which can form large crystallites. Photocurrent was established to increase up to 20 times in the CZTSe/polyaniline/ FTO/glass heterojunction in comparison with the polyaniline free structure. In the heterojunction, polyaniline acts as a hole transport layer improving the charge transfer to the FTO electrode and preventing circuit shorting because of porosity of the CZTSe film. Keywords Electrodeposition . Polyaniline . CZTSe . Photoelectrochemistry Introduction Semiconductors CZTS, CZTSe, and CZT(S) Se are promising light-absorbing materials for thin-film solar cells. According to their structural properties, these materials belong to kesterites. Their advantages, along with a high optical absorp- tion coefficient of up to 90% and an optimal band gap of 1.0– 1.5, include the wide distribution and relatively low cost of components, as well as the possibility of using this materials for the manufacture of a new generation CZT(S)Se/polymer- type hybrid thin-film photocells [1–5]. To date, a number of diverse technologies have been de- veloped for the production of thin films of complex chalco- genides CZTS and CZTSe such as sputtering [6], photochem- ical deposition [7] and the SILAR method [8]. But the method of electrochemical deposition deserves the greatest attention [9–12]. This method allows the process to be carried out at low temperatures and to control the film thickness by chang- ing the potential and other electrochemical parameters. Electrochemical deposition of metals and alloys (Cu, Sn, Zn) is a well-established technology and has been used on an industrial scale for many years. Therefore, the electrodepo- sition of such alloys in combination with sulfur, selenium, and tellurium is especially promising. Electrochemical methods have been successfully used to obtain thin films of semicon- ductors CdSe [13], CdTe [14], CIGS [15], CZTS [16], and others. Electrochemical methods for producing CZTSe attract particular attention due to the low cost of equipment and re- agents, as well as low material costs and material losses upon receipt of films [10, 12]. A new direction in the use of film semiconductors CZTSe is the creation with their participation of hybrid and cascade photocells with improved photo and energy characteristics. It is known that the important components of any photovoltaic cell, including organic solar cells, are the active layer in which charge carriers are generated and two electrodes on which holes and electrons collect [17]. However, a typical solar cell structure may include additional layers located between the active layer and one or both electrodes. Such additional layers are called “buffer layers” or “interfacial layers” which are important for solar cells. Therefore, the appropriate choice of materials that make up these layers, the methods of their de- position, and the optimization of their thickness play an Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10008-020-04801-0) contains supplementary material, which is available to authorized users. * Kazhmukhan Urazov u_kazhm@mail.ru 1 D.V. Sokolsky Institute of Fuel, Catalysis and Electrochemistry, Almaty, Kazakhstan 2 Frumkin Institute of Physical Chemistry and Electrochemistry, Moscow, Russia 3 Institute of Physical Sciences and Technology, Almaty, Kazakhstan https://doi.org/10.1007/s10008-020-04801-0 / Published online: 12 August 2020 Journal of Solid State Electrochemistry (2021) 25:237–245